As in, does it mean a F-22 can literally fly right into the middle of Russia or China, drop a bomb, and fly back home?
Or does it mean these aircraft become difficult to track, but still possible, like having a manhunt after an experienced hunter.
Also, can other fighters lock onto stealth fighters?
http://www.defencetalk.com/forums/air-force-aviation/brief-history-lo-10856/
That is what they were referring to.
Stealth is a mass media term. The correct term in relation to aircraft is low observable.
It means exactly that. Certain measures, (materials, shapes, electronic and infra-red emissions and so on) are designed in such a way and applied to a particular platform so as to reduce the opportunity for an opposing party to "observe" the platform that has been designed this way or has these features.
Most commonly it refers to reducing the signature of radar returns from a particular object, but it refers to the entire spectrum through which it is possible for one object to observe another object.
A radar fundamentally is a device capable of transmitting and receiving a radar signal that has a capacity to count how long that signal took to travel from the device, be reflected off an object and then return to the radar device to be counted.
The device transmits more than one signal and because it knows it's own position on the earth, can work out altitude, speed, direction and so on of the object from the waves being transmitted, received and counted. A simplistic diagram of how a radar works is attached.
Now because a radio signal has a theoretically unlimited range, the signal travels at the speed of light and mechanical devices can rapidly point the transmitter/receiver to scan across the entire sky cheaply and with great persistence, radar systems are the favoured sensor system for detecting aircraft in modern military forces.
Military aircraft however sometimes don't wish to be detected by radar systems or any other means. Sometimes they don't mind being detected but take measures to ensure that the people who have detected them can't do anything to them.
So they employ measures, tactics and varying methods of a bewildering variety to ensure they aren't detected or if they aren't, they aren't tracked. Or if they are tracked that perhaps they can't be engaged (with a weapon).
These measures can be as simple as a submarine travelling underwater, or an aircraft flying behind a Mountain range, meaning neither can't be seen. Those are examples of tactics to ensure that your platform is not observable.
Aircraft fly low sometimes which means they can fly underneath the search patterns of general air search radar systems. With no radar beams hitting the airframes, the radar systems aren't getting any reflected radar energy.
Modern aircraft also use certain shapes, structures and materials to deny a radar system a meaningful amount of reflected energy. As I'm sure you can imagine a flat metal plate makes a pretty good reflector. A curved metal plate makes a pretty good one too.
A plate made of composite materials however makes a less good reflector. One that isn't flat but is shaped in certain ways makes an even less good reflector. The purpose of shaping when talking about a low observable aircraft is to direct energy along a certain path away from the path that will see the energy return strongly to the transmitter/receiving device.
A plate therefore shaped in the right way and made of the right material (usually known as radar absorbent material - RAM) is therefore going to reflect energy extremely poorly.
This is what "stealth" aircraft do. They dissipate, re-direct and absorb the energy that a radar system directs at them in an attempt to reduce the return signal the radar system sees.
If it can do so, the radar system will then find it more difficult to get accurate readings on the low observable platform in terms of height, speed, direction and so on.
Obviously this has great tactical benefit to the user because they can use their platform to approach the radar or some other target and engage it, before (hopefully) the radar user is even aware the platform is coming for them.
That is the effect that low observability has. It does not provide any sort of "silver bullet" solution and requires careful planning, tactical nous and critical thinking to employ properly, but as seen, can provide astonishingly capable results when properly employed.
Any aircraft can and will be tracked if enough radar energy can be directed onto it or if it is within visual range (by visual I include electrical/optical devices intended to improve visual range) and it's position known, or if it communicates using equipment that can be intercepted, geo-located (it's geographical position) etc.
The reason that modern low observable aircraft are being built is that it is difficult to build a radar or system of radars with sufficient coverage and power so as to be able to overcome the measures inherent in these low observable aircraft, but if such an aircraft, say an F-22A for argument's sake got close enough to a powerful modern air search radar, even it's extremely capable low observability measures would be insufficient to prevent the radar energy returning to the radar system from the platform and could then be tracked. The good thing for low observable aircraft is that they have weapons that mean they don't have to get that close before they can use them.
So much so, that there is no major military platform being built that doesn't have thought put into how the platform's own signature (the type of radar reflection it makes, what it looks like etc) is managed in some respect.
Hope this helps.