I understand "git commit --amend"

I had just known that the git command "git commit --amend" was existing. But I didn't know what it was and when/how I could use this. But when I have been researching about Bill of Rights in previous post, I understand it. Like as "amendments" re-define and re-design the last version of United States Constitution, "git commit --amend" re-defines and re-designs the last commit.