Google Adwords Function:
1. You make Your Ads:
Before creating your Google ads, you have to choose keywords which related to your business.
For that keyword research you can go the following link:
Google Adwords Keyword Tool
With Google ad words tool you can easily find profitable keywords.
2. Your ads appear on Google:
When somebody searches your targeted niche or keywords on Google, your ad may appear on the Google search engine result page depending upon your website rank. Now you are basically advertising your website whoever interest will click your ads.