If 2 goes into 5 two times, then 7%(5//2) = 7%2 which would be 3.5, but 3.5 isn't an answer.

Question

I need an explanation...

Answer 1

X%Y = X - (X//Y)*Y
7%2 = 7 - (7//2)*2 = 7 - 3*2 = 1

Answer 2

7 % 2 = 1
(https://en.m.wikipedia.org/wiki/Euclidean_division)

Answer 3

% isn't the division operator, it gets the *remainder* of a division

2 goes into 7 three times, and then gets the remainder: which is 1

Thus, 7 % 2 returns a value of 1

Answer 4

The % is modulo; it deals mainly with dividing whole numbers, and gives you the remainder when it reaches it's limit.

EG: 7%2
So first we see how many times 2 will fit in 7 as a whole number:
2 x 1 = 2 - still lower than 7
2 x 2 = 4 - still lover than 7
2 x 3 = 6 - still lower than 7
2 x 4 = 8 - higher than 7

Now to complete the modulo, we do 7 - 6 which equals 1, your result! Your program does these calculations for you, all you need to understand is you are seeing what's left over, not the result of a division.