Floatin' down by his feet was the letter from his sister
Second grade handwriting simply read "I miss ya"
Suit jacket pocket held his baby daughter's picture
So the dead dude has tragically left behind a crushed younger sister and a little girl of his own. Lupe is cleverly giving us a background to the protagonist without bluntly stating facts. Good storytelling techniques.
To help improve the meaning of these lyrics, visit “The Cool” by Lupe Fiasco Lyrics and leave a comment on the lyrics box