When you are searching Primo, use the language filter on the left side of the screen to select the languages that you are comfortable reading. To keep this filter in place for the duration of your session, see instructions here.
In individual databases, you can usually find language options on the advanced search screen. Some databases default to advanced search, so you'll see limiting options right away. If you don't see enough options on the initial search page, look for an "advanced search" link, then scroll down until you see language choices. Select the languages that you read before you launch your search!