What does this syntax for assigning names to variables mean?

I'm new to maple and I'm trying to write code in worksheet mode with some source code I have, I don't understand some of the syntax though, like the next:

m,  mass
r,  radius

J=m*r^2; Inertia

m and r are variables, so does this syntax mean that after the comma I set a name or label to the variables? because I tried to follow the same logic with 2d input math but it doesn´t work.