Sure we use letters and numbers to represent them, and words for many musical concepts, but people have been making music without knowing these and since long before they were codified..
The number line is a continuous stream, right? Carrying on from my earlier comment [0], an alien species could use a smooth gradient of colors to represent numbers; their senses may be such that they interpret a distinct shade, or a "step" or "tick", after a small difference in wavelength/frequency, and they use those steps to represent integers, and a transition between two shades to represent fractions..
So if I want to tell you I want 1 of something, I just show you a deep violet. If I want 2, I "say" a ever-so-slightly less saturated violet. Green may mean a million, and reds would be used for astronomical scales. :)
But they may not "think" in terms of "numbers" as we do; they would just see and imagine colors and associate them with a sense of quantity, or comparison..