You can split the text using tokenat and tokencount expressions. You will probably need to get rid of all punctuation before doing that (use replace expression).
You can't store multiple words in one variable, you should use an array.
To check the length of each word use len expression.
construct.net/en/make-games/manuals/construct-3/system-reference/system-expressions
Also, check this demo:
howtoconstructdemos.com/split-text-into-separate-words-c3p