Thank you so much, Hallie!!! ^^

"Can't knock" means you can not say anything bad (about something) usually because that the object is legitimate or good. "the hustle" can mean working really hard or can mean trying to make money by any means (often dishonestly, illegally, or through trickery), or can mean getting people to support a business project. So "can't knock the hustle" probably means that the hustle is above reproach. The rest of the song should say more about what kind of hustle we're talking about.

好吧，我仿佛已经大概了解了。MD......