My Car Engine Has No Compression, What Does This Mean?

An engine is essentially a self-powered air pump, so it needs good compression to run efficiently, cleanly and to start easily. As a rule, most engines should have 140 to 160 lbs. Of cranking compression with no more than 10 per cent difference between any of the cylinders. Low compression in one cylinder usually indicates a bad exhaust valve. Low compression in two adjacent cylinders typically means you have a bad head gasket. Low compression in all cylinders would tell you the rings and cylinders are worn and the engine needs to be overhauled.
First make sure you are measuring it right. Compression can be checked two ways: Manually with a compression gauge or electronically with an engine analyser. With electronic testing, a computer analyser estimates compression in each of the engine's cylinders by measuring slight variations in engine cranking speed. The results correlate well with actual gauge readings, and can be completed in a matter of minutes without having to remove any spark plugs. Furthermore, the analyser prints out the results of the compression test making it easy to see and compare the actual numbers.
To check compression manually with a gauge, all the spark plugs must be removed. The ignition coil must then disabled or the high-tension lead grounded. If the engine has a distributorless ignition, the ignition coils must be disabled to prevent them from firing. The throttle must also be held open. The engine is then cranked for a few seconds using a remote starter switch or a helper while a compression gauge is held in a spark plug hole. The maximum compression reading is noted, then the process is repeated for each of the remaining cylinders. The individual cylinder readings are then compared to see if the results are within specifications. Always refer to a manual for the exact compression figures for your engine because they do vary from the ballpark figures quoted earlier.

I was driving my grand am 2002 (140,000miles) at a speed of 70mph on the high way with no noticeable symptoms of engine failure for about 40 minutes when the engine turned of. My car no longer has compression the starter,spark plugs, coils, fuel pump, and battery works but my car wont start. What is wrong with it.

If there is no compression, it could be very serious and the cost he noted sounds very possible.  Low compression means that the cylinders are not air tight and the ignition of the fuel is not complete.
However, I would get a second opinion and ask another mechanic if they agree with that diagnosis.  I would suspect that you would have had some problems before the no start problems if it is low compression.  Such as oil consumption, loss of coolant, low power, missing, low fuel mileage, engine noises, overheating.   Not necessarily all but probably 3 of the 6 symptoms listed above would probably occur with the most likely causes of low compression.
If low compression is verified, it is probably a good time to test the money in a newer vehicle.  Good luck.

I just bought a hyundia and was driving it home the same day going round a round a bout and it just stopped. It has no compression in the motor what the hell is wrong with it?

This promblem occurs due to any faut in cooling system. The most common faults are
1) radiator tubes may be damaged .2) unworking of water pump.3)there may any leakage in upper pipe. 4)head gasket may be damaged.because of this promblems the engine get overheated. 
  The low compression may occur due to 1)damage of head gasket 2)piston compression rings may be worn out.
3)cylinder bore may be worn out.