Search engines read the page text to know the topic of a page and there are three tags that specifically alert the search engine to what a page is about; the title, description and keywords tag. Yola provides an area to edit these tags.
If you click Page > Metadata, you will find fields to enter unique title, description and keywords tags for each of your site's pages.
For more information, please take a look at this tutorial: Adding title, description, and tags