For example, here's what a commit might look like:
$ git commit -m 'adding stuff and things'
[master (root-commit) 751936d] adding stuff and things
2 files changed, 0 insertions(+), 0 deletions(-)
create mode 100644 stuff
create mode 100644 things
See how git is explaining what it's doing?
What if I try to do something it won't allow, like committing no change:
$ git commit -m 'useless commit'
On branch master
nothing to commit, working directory clean
Here git tells me that there was nothing to commit, so no commit was made.