i'm trying to submit a run but i don't know what this means

New Game + is basically a rule that states you cannot exploit anything left over from a previous playthrough. Examples are in the game's rules

For ILs, as explained in the rules, for NG+ having access to the Director Mode Menu and bringing additional Vehicles into the Mission/Hobby is allowed.

For non NG+, you aren't allowed to smuggle a vehicle into a mission, except for street races where you can start with any vehicle.

so if i skip part of a mission after failing it 3 three times that would be considered NG+

Thanks for asking this, I didn't know what it meant either.