How do I let my friend edit my Replit app without giving her my password?

The Invite button lets you add her by username/email so she edits with her own account, you'll see each other's cursors live. Which features need a Teams plan changes every few months, so check what the invite dialog offers on your plan.

Whatever you do: change your password now, and turn on 2FA, since she had it.

Second option that scales better: connect the Repl to GitHub, add her as a collaborator on the repo. Then she can work in Replit or anywhere else, and you have history of who changed what.

Live multiplayer is nice, but you're editing the same files at the same moment. Agree who works on which part.