'אף' means 'nose'. However, is also means (according to the tips and notes of this lesson) "not a single". Hope that helps you.
Also, I would recommend a website called doitinhebrew.com to look up words you are unfamiliar with.
You can also use the Reverso app. It's free or pro is $10 a year and has sound/pronunciation and tables, and saves all your vocab searches. But it's only available on the app. The website doesn't have audio for Hebrew.