Fork
A personal copy of someone else's repository, made with one click. Making one involves writing no code.
What it tells you about a developer
Separate authored repositories from forks before crediting a developer with a project. Forks followed by merged contributions back to the original show genuine open source participation. Untouched forks show interest.
Developers fork projects to experiment, or to prepare a contribution back to the original. On a profile, forks are labeled and sit alongside original repositories. A high fork count on a project a developer authored means many people copied their work to build on it. That is the positive reading of the same word.