CPC (cost-per-click) is the average cost of a click on a paid search result on a keyword.
A 'click' on a PPC (pay-per-click) campaign represents a visit or interaction with your company's product/service. When you advertise, your CPC will always be less or equal to the maximum defined budget. Your actual cost-per-click depends on both you and your competitors ad rank, maximum bid and quality score.
For more information on CPC bidding please read Google’s official documentation.