To clone a Git project is to make a local copy of a repository that may be hosted elsewhere. It is like receiving your own copy of a shared notebook, including its saved history.
A developer can clone a website project onto a computer, make changes, and run it locally. The original shared project remains separate until changes are pushed or otherwise shared.
Cloning a project does not mean every secret or service setting is included. Check the project's instructions and only work with code you trust.