QUICK ANSWER
"Nada" is a form of "nadar", an intransitive verb which is often translated as "to swim". "Tu" is a form of "tu", an adjective which is often translated as "your". Learn more about the difference between "nada" and "tu" below.
nadar(
nah
-
dahr
)An intransitive verb is one that does not require a direct object (e.g., The man sneezed.).
tu(
too
)An adjective is a word that describes a noun (e.g., the big dog).
1. (informal) (possessive)
A word or phrase used to refer to the second person informal “tú” by their conjugation or implied context (e.g., How are you?).