CPC stands for Cost Per Click, which means the price of a single click on an ad that a visitor will click on your site. example: Ad1 has a $0.50 CPC and you have 4 visitors on your site that will click that ad once. Your profit will be $2 because the cost per click is 50 cents, hence 50 cents times 4 clicks will give you $2 dollars.
CPC aka Cost per click is often used when advertisers have a set daily budget. When the advertiser's budget is hit, the ad is removed from the rotation for the remainder of the period. For example, a website that has a CPC rate of $0.10 and provides 1,000 click-throughs would bill $100 ($0.10 x 1000). The amount that an advertiser pays for a click is usually set either by formula or through a bidding process. The formula used is often cost per impression (CPI) divided by percent click-through ratio (%CTR).