To get help on a Git command, Google git + command. The first result will be a link to the Git documentation. There you'll find the complete documentation of the command.
We can also access the same page from the Git Bash. Just run git command --help. So, for example, if we need help with the config command, we run:
git config --help
The same information as with Google will come up. Use the space bar to go to the next page. Use q to exit. If you only want to see a summary of the command, run:
git config -h