Graph theory?

The (v 2) part, written vertically, appears to be the binomial coefficient vC2, the number of combinations of v things taken 2 at a time.
The v is actually a Greek letter nu, and I think here it stands for the number of vertices.
The e is epsilon, and I believe that it stands for the number of edges.

In a simple graph, you can't have the number of edges exceed the number of combinations of the number of vertices taken two at a time.

Graph theory notation is all over the place. I hope your book has a glossary of notation. See http://www.math.illinois.edu/~dwest/igt/notat.html for a discussion of notation.