Firebase Geofire get near by places

I have an app that i need to find places near by, i am using firebase realtime DB
i want to get the places near by me (device location), and i don’t finding any examples to do that.
How to save the data, with location based on geoFire, And how the fetch the data by location and distance.
Another question is what unit geoFire radius/distance using? KM / Mile ?
Thanks for helping.

any solution for that???