Question

When I run git commands like git commit or git log --shortstat part of the output looks like:

2 files changed, 3 insertions(+), 11 deletions(-)

What is the meaning of an insertion or a deletion?

Answer 1

It is just number of lines inserted and number of lines deleted in that particular commit. Note that a modified line maybe treated as an insert and a delete.

Git log manual:

–shortstat

Output only the last line of the –stat format containing total
number of modified files, as well as number of added and deleted
lines.