100Mbps == 100 Megabits per second == 100,000,000 bits for
second
A simple and rough calculation to convert bits to bytes in a
network connection is to divide the bits per second by ten.
So 100Mbps is approximately equal to 10 Megabytes per second.
Why is it divide by 10?
1 byte == 8bits
+1 Start bit + 1 Stop bit.
So total, you will need 8+1+1=10bits.
The actual bytes per second bandwidth is lesser since the above
calculation does not take into the consideration of synchronization
characters, parity bits, Address information and Error Checking
bits.
If you are interested to find out more, you have to study data
communication, which is part of electronics engineering.
