What are unknowns in linear systems?

I am studying linear algebra right now and my textbook says something about unknowns in linear systems. The number of linear equations is represented by the variable "m" and the unknowns are represented by the variable "n". I have tried researching what unknowns are in the internet but could not find any answer to my question. As a result, what are unknowns? Are they the coefficient's of each variable in each equation? Thanks

The unknowns are just the variables. E.g. if I have the system $$x+y=1, \quad x-2y=7, \quad 3x+4y=12$$ that's a system of three equations in two unknowns ($x$ and $y$). So in this case $m=3$ and $n=2$.