What is this?

can somebody help me with this silver medal?

silver

What does the reverse look like?

Any hallmarks on it?

BM likely stands for Bene Merenti. This appears to be an unofficial production (privately made). Possibly French or from the Vatican. Seeing the reverse might help!

Thank you! There isnt any hallmark on the reverse.

@Kaotik is correct, looks like an early 20th C die-stamped award, unofficial production. BM is indeed Bene Merenti.

Thank you! is this valuable?

Not particularly, no. Unofficial, privately made pieces like these are not very collectible. Especially if you don't know the original owner and the story behind the piece.