Google AdWords is a pay per click service. You create ads and when someone clicks on your ad you pay Google. You can limit how much you might spend by setting a daily budget.
If you want to receive money from people clicking on ads on your website, that service is called Google AdSense. You need to sign up separately for that.
Hi @Vinay M,
Campaign Budget : An amount that you set for each ad campaign to specify how much, on average, you'd like to spend each day. You set an average dailybudget for each AdWords campaign, and then the system will aim to show your ads as much as possible until your budget is met.
You will pay in Google AdWords and Google will pay you in Google AdSense.
Hope this helps,