How am I to understand this notation with regards to bdS and the int S? $S=\bigcap_{n=1}^{\infty}\left(-\infty,7+\frac{1}{n}\right]$

Question

I'm trying to find the largest $\epsilon$ such that the neighborhood centered at $x$ of radius $\epsilon$ is contained in $S$.

That part I think I can do, but I just don't know understand the below set.

$x=-1$

$S=\bigcap_{n=1}^{\infty}\left(-\infty,7+\frac{1}{n}\right]$