PPC stands for Pay Per Click.

Its like a huge game. The object of the game is to have better expectations than your opponent.

For example,

Lets say you are selling an Apple. Your first task is to find out what keywords you are relevant for...its not always so easy. It could be "Tasty Apples" or "Ripe Apples" or any other variation. But you wont get any exposure if you try advertising "Coca-cola" for example.

You will gain exposure to Amazon customers. Exposure is called "impressions" in the PPC world.

You have an apple. You must determine if this apple is more appealing than your opponents apple. If you think its gonna be a super appealing apple, you should try to pay for exposure. You determine how much you pay for exposure by setting something known as a "bid". The more you pay for exposure, the more you are shown on Amazon.com.

But its possible you are paying too much for exposure...and now you do not have any profits. Maybe your opponent is not being shown that much, but they are getting more profits than you. At that point, you should not pay that much for ads (reduce your bid).

The goal of this game is to make as much profit as possible.

PPC is insanely harder than this and I could spend hours trying to tell you everything. Its like Chess. Its easy to understand but ridiculously hard to master. I would advise trying to learn more about PPC in general or maybe having a professional do it.