Person I don't know listed on Find My App.

I was poking around in my settings and opened the Find My app for the first time. Never needed it so never opened it. When I opened the app a number was listed that I did not recognize. I did a search and the number belongs to a woman who lives about 3 hours away from me. I've never opened the Find My on my phone so I have no clue how or when this number was added to the app.

1. How could this possibly happen? My password is pretty lengthy and includes all the things. Is there some sort of prompt that pops up on my phone to give that person permission?
2. Is there any way I can tell when this started?