How does Google target ads to AdSense for search queries?
AdSense for search uses Google search to return search results to end users. The search results that appear on a AdSense for search results page will be very similar to those that appear on Google.com. Google ads are targeted to these results based on our targeting algorithm, which takes words and phrases included in the query and matches them to relevant ad campaigns.
Ads are also matched to the language of the query - for example, a search using a French query will generally return ads in the French language. Ads in other languages may appear, due to advertisers' targeting decisions.