MH or Mega Hashes is a speed of measurement for crypto mining equipment. The larger this number the better. The larger this number the faster your equipment will perform and should be more successful.  A mega hash is equal to 1000 kilo hashes.

Kilo hash 1-999

Mega hash = 1000 Kilo hashes

Giga hash  = 1000 Mega hashes

Tera hash = 1000 Giga hashes