What are the 5 tempo markings?

What are the 5 tempo marking?
How do musicians know how fast to play a piece? And why are the terms in Italian?
Grave – slow and solemn (20–40 BPM)
Lento – slowly (40–45 BPM)
Largo – broadly (45–50 BPM)
Adagio – slow and stately (literally, “at ease”) (55–65 BPM)
Adagietto – rather slow (65–69 BPM)
Andante – at a walking pace (73–77 BPM)