Is there a reference for math like there are for programming languages? What do you do?
Also like with programming languages, there are communalities that are valid most of the time. Simple examples that you probably know are the way we write numbers, using + for addition, using {} to denote sets, ℝ for the real numbers, etc.
You’ll find that many math books start with an overview of the notation used.
https://en.wikipedia.org/wiki/History_of_mathematical_notati... mentions tons of specialized notations (most of which, I guess, you won’t need to know about)
Most of this is explained through coursework and instruction in the relevant domains where when you hit something you don't understand you ask your mentor/teacher/colleague/the original author what something means.