A query is a Coveo Search API request that retrieves results. With Coveo, a query is counted when conducting a search, applying a filter, choosing a facet, sorting results, and navigating to a search results page.
Some search products track a query for every character that is typed in the search box, often referred to as search-as-you-type. Coveo predominantly relies upon query suggestions, only counting a query once the user submits the search. Search-as-you-type is of course available through Coveo, but can result in significantly more queries.