I'm starting a book on generalized analytic continuation and the phrase 'closed linear span', which I haven't encountered, has popped up several times in the introduction. The first context was: for each $n\in \mathbb{N}^+$, let $S= \{z_{n,1},\ldots, z_{n,N(n)}\}$ be a finite set of points in $\mathbb{D}_e=\{z \,:\, 1\leq |z|\leq \infty\}$, and define $$ R_n := \bigvee \left\{ \frac{1}{z-z_{n,j}}: 1\leq j \leq N(n)\right\}; $$here it claims $\bigvee$ is the closed linear span, which is where my question begins.
My intuition says it is similar to the normal concept of span in a vector space. At some point or another I've taken courses in linear algebra, complex analysis, and measure theory- if those are relevant- but I haven't taken any functional analysis. Any advice would be appreciated.