An equation has terms, variables, constants and coefficients.
A term is the part of the equation that is separated by addition or subtraction signs.
A variable is usually symbolized by a letter in place of an unknown value.
The coefficient is the number before the variable, the ones that multiply it.
The constans are the known values or numbers that appear in the equation.
For example:
3X+16
This equation has two terms "3X" and "16"
One variable "X"
One coefficient "3"
One constant "16"