Google Adwords is a tool for advertisers to direct traffic to their web pages to hopefully create in one way or another some kind of a sale. It is basically someone running a Google Adwords campaign and Paying per Click (PPC) for the ad to be advertised by Google. The advertiser does not necessarily target your website especially,

Google places the ads wherever the content is relevant to the PPC ad they asked for. Being involved with google adwords is something that takes time to learn there is higher costs for higher demanding keywords you are trying to promote at. Purchasing from adwords has great returns if you are selling something, but if you depend on just advertising to hold up your site then it's no good for you because of the price it comes at.