I would love to have an overview on a project repo, explain to me which files does what without me opening them. For a piece of code, unless it is badly written

I would love to have an overview on a project repo, explain to me which files does what without me opening them. For a piece of code, unless it is badly written, I don't think I need explanation. But higher level explanation is good. Maybe we can extract call graph and comments from a repo and produce some useful overview that way.