The constant is 6 because it's the term without any variables attached to it.
The coefficients for terms 3x and 2y are 3 and 2 in that order. The coefficients are the numbers to the left of the variable.
The variables are x and y. They are placeholders for numbers to be plugged in later.
There are 3 terms where each term is separated by a plus sign or minus sign. The 3 terms are: 6, 3x, and 2y.