In Git, pushing means sending your saved commits from your copy of a project to a shared copy. It is like placing your finished notes on a shared shelf so other people can get them.
After committing a change, a developer may push it to a hosting service so teammates can review or use it. The shared branch may have moved forward, so Git can sometimes ask you to bring in updates first.
Push shares saved commits; it does not publish a website by itself. A separate deployment step is usually needed to make a website change live.