If you click the Floppy Drive icon ONCE only, Win98 will show you the following visual information about the diskette:

MB stands for "megabytes" which is 1024 "bytes" - the storage space needed to store a single character.

Why not a goold old fashioned one thousand bytes?  Because computers think in multiples of two, and
1024 = 2x2x2x2x2x2x2x2x2x2