A "lemon" is a car that is dysfunctional, even though you had no idea when you bought it. Clearly, cars do wear down over time, just like any other product. Repairs are expected. However, if the car is not up to the realistic standards for a vehicle, then you need to get your money back from the company that produced it. You have rights as a buyer.
How do you know if the car is not up to those standards? There are some repair requirements that have to be met. Specifically, under West Virginia law, the car needs to have a "substantial nonconformity" that you find after you make your purchase. You then have to use the warranty to try to have it repaired. If this is unsuccessful, despite a "reasonable" number of attempts and the car is still defective, then it may be a lemon.
In short, the vehicle needs to have massive defects that appear to go above and beyond the norm, and which also prove impossible for the company to repair. This makes the car essentially unusable. If it was any other product, you'd want to return it, but that gets tricky with something as expensive as a car. Lemon laws are meant to protect you and allow you to get the type of car you deserve.
Some states have lemon laws only for brand new cars, but West Virginia covers cars that are new to you, even if they are used when you buy them.
If you think that you do have a lemon, you do not have to simply accept it. Make sure you understand all of the options that you have.