what does 7% (2//3) meant ?

Answer 1

// performs the euclidian division.
% gives you the modulus, ie the remainder of the euclidian division.

For example:
42//9 = 4 and 42%9 = 6 because 42 = 9*4+6.

7% (2//3) is probably undefined since I don't think modulo 0 has any meaning.

Answer 2

// gives the quotient
while
% gives you the remainder

Answer 3

i dont no