Computers store information in blocks of bits called a byte. 8 bits are in a byte. When you see a USB thumb drive that hold 1GB (Gigabyte), that drive can store 1 billion Bytes.

One byte is a representation of another number.  For example the following bytes are converted to decimal format.   Other options are Octal, or Hexadecimal.  Depending on the program deciphering the bytes, they can mean anything they are coded to represent.    0000 0101 can represent 5 or the letter A.

0000 0000  =  0
0000 0001  =  1
0000 0010  =  2
0000 0011  =  3
0000 0100  =  4
0000 0101  =  5
0000 1000  =  8
0000 1111  =  15
0001 0000  =  16
1111 1111  =  255

Bytes are generally measured in the range of thousands to billions.   So to make it a bit easier Byte quantities are described with the naming metric conventions.

8 bits = 1 Byte
1 000 bytes = 1 Kilobyte
1 000 000 bytes = 1 Megabyte
1 000 000 000 bytes = 1 Gigabyte
1 000 000 000 000 bytes = 1 Terabyte
… Petabyte, Exabyte, Zettabyte, Yottabyte