There is an expression on each side of the equals sign.
The variables are x and y.
The coefficients are 2 and -4 (note: you may either add -4y or subtract +4y)
The like terms (which may be combined) are 3 and 7. Let's combine them:
2x+3y=4 (subtract 3 from each expression)
The 2 and x are factors (they are multiplied); the (-4) and y are factors.
Algebraic equations are meant to be precise, concise representations. Be sure to learn the terms well.