The song is about Trick Daddy boasting that no one can do anything like him, especially when it comes to loving (or providing carnal pleasure to) Trina.
The word "Nann" could be said to mean "no", "none" or "not one"; the resultant statement a double negative typical of southern vernacular: "You don't know "no" nigga like me..." Other possible interpretations could be that "nann" is a disambiguation of the colloquial "nary", meaning "not a" or "not one," "any other," or "never a".
This is typical of Southern AAVE rap, which deploys aggressive vowel merging and final dropping to ease rhyming.
The music video for "Nann Nigga" directed by Zodiac Fishgrease features Chico Debarge, J.T.
Money and then Indianapolis Colts running back Edgerrin James, who, like Trick Daddy, resides in Miami, Florida.