Thank you for your interest in GSoc2022.
Before applying for GSoC with Sagemath, you should start getting familiar with Sagemath (how to play with graphs, do basic algorithms, etc.) and with the developer guide
http://doc.sagemath.org/html/en/developer/index.html (what’s the programing standard, how to use git, etc.). Then, you can start contributing Sagemath with smalls patchs (implementation of a new algorithm, improvement of an existing algorithm, improvement of the documentation).
David.