Distance is measured in a unit of length like feet or kilometers. For example, typical WiFi links are only one or two hundred feet while a link that goes to a geostationary satellite is 36,000 kilometers (each way). We are all familiar with units of measure for length -- inches, feet, meters, miles, etc., and can easily convert among them. (How many miles is 36,000 kilometers)?
How about speed? If we are talking about a car, some measures of speed are miles/hour, kilometers/hour, miles/minute, inches/day, etc. Again, you can easily convert between these. (How many miles per minute is 60 miles per hour)?
In general, we can say that measures of velocity are of the form: length/time.
How about data communication speed? Some examples are bits/second, bytes/second, bits/minute, etc. You can also convert between these. (How many bytes per second is 1000 bits per second)?
The general form of measures of communication speed is: quantity of data/time.
We are familiar with measures of time -- seconds, minutes, days, etc. -- but what about quantity of data? The smallest quantity of data is the bit. The more bits, the more data. There is little information in a single bit which can only differentiate between two choices like yes and no or female and male). A text email might require a few thousand bits, a hi fidelity song 20 or 30 million bits, and a hi definition movie 100 billion bits -- that is a lot of information.
Of course, a billion random bits convey nothing -- meaningful information requires order, a coding scheme like ASCII or Paul Revere's "one if by land and two if by sea."
The more bits one has to transmit over a link, the longer it will take, but it will take less time over a fast link than a slow one.