Normally, your speed will be labeled as
X.XXMbit instead of MB, because normally, Megabyte is abbreviated as MB. You'll see it all over Windows like that. The proper abbreviation for network speeds is Mbit, for Megabit. Same thing goes for Gigabit ethernet speeds, it's the same exact principle, just uses bits instead of bytes.
When talking about network transfer speeds, everything is divided down into bits instead of bytes. The bit is the smallest form of data, and 8 bits make a byte. Digital data can be transmitted by 0's and 1's, which are the binary bits that a computer can interpret as data.