It's a combination of the words entrepreneur and negro. Taking the smart business aspect of the first word, and combining it with a less insulting but still common term used in a friendly manner within the hip-hop culture as a greeting. These two words together describe what would otherwise be considered a homie.
Jon: It's all good, I'll front u a bill, just hit me back when u got it.
Pekelo: Hell yeah, that's my entreponegro.