An operator is a function that is written as a word. Well its all about LaTeX. It is defined as 118em where the em is taken from the current math symbols family see Units of length.
LaTeX provides the commands that follow for use in math mode.
You can use label to give an equation an identifier that you can use to refer to it later and then use ref or eqref within your document to insert the actual equation number at that location as a reference. More symbols are available from extra packages. The align environment will align the equations at the ampersand. This reference sheet is intended for those seeking some clarity about inline math and LaTeX equation syntax the only math function available in Notion.