What does this mathematical notation mean? Please excuse this simple question, but I cannot seem to find an answer. I'm not very experienced with math, but I keep seeing a notation that I would like explained. The notation I am referring too generally is one variable m floating over another variable n enclosed in paraentheses. You can see an example in the first equation here.
What does this mean? Thanks in advance for the help.

That is a binomial coefficient. $\binom{n}{m}$ means the number of subsets of size $m$ of a fixed set of size $n$.
