Every real project needs a history. Git records each change you make to your code, so you can see what changed, undo a mistake, or try an idea on a separate branch without risking the working version. It is as useful on a solo Android app as on a team project.
Git lives on your machine; GitHub and GitLab are where the repository lives online. They give you a backup, a way to share code, and tools such as pull requests (merge requests on GitLab) for working with others. Android Studio has Git built in, so you can commit and push without leaving the IDE.
Learn the core commands first, then see how they apply to an Android project. When you're done, continue on to UI with Jetpack Compose.
A freeCodeCamp crash course by Sumit Saha: how Git works, core commands, branching and merging, pushing to GitHub, stash, revert, and rebase.
How to commit and push an Android Studio project to GitHub from inside the IDE, step by step.
Gwen Faraday's freeCodeCamp course on installing Git, cloning, committing, branching, SSH keys, undoing changes, and forking. A second take on the basics if you want more practice.