Can anybody teach me about functions domains and range?

Functions are graphs that do not have repeating x-values. The domain of a function are the x-values and the range are the y-values in a function

To make something a function the x cannot share multiple Ys(the vertical line test) but the y can share as many Xs
For example:
(1,3) (1,-6) would not be a function but...
(1,3) (2,6) would be

The domain is the x value. In a table it will almost always appear on the left side.

The range is the y value. In a table it will almost always appear on the right side.