Help with text analysis - UNIX

Hey Guys

I recently posted yesterday about trying to count the amount of separate words that exists in a text file e.g. walle.txt.
i want the output to give to give me a list of words with a number next indicating how many times its came up in the file e.g:
cat 20
the 11
if 40

I'm completely new to Unix, I'm currently using the bash terminal from a Macbook Pro. I am running this on some example file scripts, is what i'm trying to do possible? if so please help.

Thanks