I am a beginner in programming. I chose to start with python. While exploring it, I found out that you can call Functions with variables.
f('foo') #returns 'foo'
There is no special name for it, but there are two related concepts that you should look into
A function is a first class object. Just like a variable, it can be assigned, passed as argument, returned as value. Contrary to a variable, it can be called by using parentheses