How does git roll back a single file to a specified version?

1. Go to the file directory where the file is located, or find the file path.

View File Modification records
Git log mainactivity. Java

2. Roll Back to the specified version

Git reset f7a220761c312d47013c394d750528f9acbc3099 mainactivity. Java

3. Submit to local

Git commit mainactivity. Java-M "reset to revision"

4. Update to the working directory

Git checkout mainactivity. Java (or git pull. Update the entire directory)

5. Submit to remote Repository

Git push origin head: refs/For/branch name

In this way, the specified file is rolled back to the specified version.

How does git roll back a single file to a specified version?