Pywikibot is a Python-based framework to write bots for MediaWiki (more information).
Each function of the library should have the description of its parameters in its documentation. This doc is present in-code, below the function declaration.
You need to find at least five params without description in the _pywikibot_ directory, understand the part of code to know what it does, add the following desc, and submit your change. Please take the time to understand the syntax of already present description fields to follow it.
You are expected to provide a patch in Wikimedia Gerrit. Documentation on Gerrit is available.