Researching Project Options
Has a very well documented wiki on how to build the project and begin contributing, also has a well-documented list of bugs or features to implement. It is written in a mix of C++ and Java so depending on the bugs or features we choose could require learning a new language https://wiki.openoffice.org/wiki/Development#Get_the_source_code_and_start_building
Well documented, newb friendly, extensive wiki. Almost everyone knows how to use it. It may be difficult to get code approved.
https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Introduction
I think doing something with DuckDuckGo would be interesting. I came across it while doing some research on more beginner-friendly foss projects.
https://github.com/duckduckgo
We have a lot of projects to choose from within DuckDuckGo's repo. There are larger projects like the main website, iOS application, and the Android Application. Also smaller ones like the Chrome Extension, Help Pages, and the Community Platform. These projects come in a variety of different languages such as Javascript, C++, Swift, Java, Perl, etc.
Not to mention the community is great, and there's tons of documentation!
Osu! is a fun beatmapping rhythm game with a huge following. Not only does it have a lot of players, it has a lot of developers, as it's an open-source game. It programs in C# and has a very easy to access list of issues that need to be fixed in 28 different repositories, including the ability to easily filter easy issues for beginners. Bugs are frequently reported and fixed right through Github itself, so it could be a fun project.
https://github.com/ppy