So, let's break this down into simpler terms:
Using a binary representation of 4 bits, let us present:
0101 (decimal 5)
0011 (decimal 3)
= 0001 (decimal 1)
5 AND 3 equals 1
So, what is happening here?
The AND compares 5 and 3's bits (as binary) if they equal a 1 or 0 in the length of AND'ed bits. You can see 5 (0101) and 3 (0011) have a far right bit that is the same to the other number, that being 1 (0101, 0011).
If it is the same in any of the bits, the AND operation will equal 1, otherwise 0. If both the decimal numbers are the same, it will equal whatever the numbers are.
Just something quick I wanted to write up after finally understanding what an AND operation is. Thank goodness for Wikipedia.