What is .word in the end of return?

Actually, the machine only knows what it will do with every position where you write a 'name'. It doesn't in fact read the name, to it it's just a code that means "this position, which is named 'name' will be coded accordingly with that which the function 'map' is already preprogrammed to do".
It's a common mistake when we are beginners trying understanding what is 'written', once that we humans are used to subjectively give written symbols intrinsic meaning, but the machine see things in a different way. You'll get used sometime, just don't give in.

you have to use the spoiler flag, otherwise everyone can see the code

spoiler flag, plz...