That nephew is Miles Morales, as in the comics, Uncle Aaron was the one who was indirectly responsible for Miles being bitten by a genetically-altered spider and gaining superpowers.
In Spider-Man: Homecoming, Donald Glover (who inspired Miles Morales’ creation following his campaign to play Peter Parker in The Amazing Spider-Man) was revealed to be playing Aaron Davis, a small-time criminal who wanted to purchase a weapon from Adrian Toomes’ crew.
Spider later tracked down Aaron for information about these high-tech thieves, and during their conversation, Aaron mentioned that he had a nephew.
The firepower they were selling was too much for Aaron’s tastes, and when Spider-Man arrived on the scene, he bailed as Herman Schultz and Jackson Brice (a.k.a. the Shockers) dealt with the superhero.