Hayden Jead

That symbol is called a bracket! It is mostly used in graphing in math classes. Brackets generally denotes some form of grouping. Another time it is used ih graphing piece wise functions. For example, if you have seen open and closed circles in graphs, the point on the closed circle will have a bracket 

Inside the {}, it contains the parameters for LaTeX commands!!

e.g. \frac{2}{5} will appear as \(\frac{2}{5}\)

e.g.(2) \sqrt{2x} will appear as \(\sqrt{2x}\)