Variables are the building blocks of your models. If you're a spreadsheet user, you can think of them a bit like spreadsheet cells. If you're a programmer, you can think of them as, well, variables.
25: constant value of 25
(0 to 1) * MyVariable: the product of a range and another variable
if VariableA > 10 then 1 else 0: self explanatory
sample(3, 5): either the value 3 or the value 5 (discrete distribution)
Note that Causal's syntax optimizes for human-readability and -writeability, i.e. you can enter $10,000 as $10k and Causal will understand.
Headcount and Average salary annual are both Variables