Terms are the numbers and variables that are usually separated by an addition sign or a subtraction sign. In the expression 2x, 3y, 5z, and 4 are all terms.
Variables are the letters that come after a number. They represent the unknown number in the equation. The x, y, and z in the expression are the variables.
Coefficients are the numbers in front of the variables. For example, 2, 3, 5, and 4 are the coefficients.
The constants are the "signs" in between the terms. These include the addition sign and the subtraction sign.