A reader at the Math 0 level has only a grasp of basic arithmetic and solving problems that employ basic arithmetical concepts. Generally, they will not have any experience with algebra.
There's no shame in being Math 0! We all started learning at some point, and Arbital aims to provide explanations of important mathematical concepts for readers of all backgrounds, including people at a Math 0 level. Even if you learned math to a Math 1 level in high school and forgot it all afterwards, we're here to help you remember what you need to know.