hello!
=======================================================
We're given the following expression:

Here,
4x is a term
3n is a term
5 is a term
4 is the coefficient of x
x is a variable
3 is the coefficient of n
n is a variable
5 is a constant
Details:-
A coefficient is a number before a variable
A variable is a letter
A constant is a number without any variables next to it
=========================================================
note:-
Hope everything is clear; if you need any explanation/clarification, kindly let me know, and I will comment and/or edit my answer :)