‘To grind’ is a very interesting word. You probably know its core meaning ‘ to crash’, or ‘to rub’. And it is the ‘rubbing’ meaning that originated some slang phrases. As it means ‘to rub an object against a hard surface’ ... in American English grind means a type of dance typically involving woman( women) rubbing their b*****s against a man’s area. ( supposedly against their harder area 😅). That’s the meaning in your book as a song is being mentioned. ‘Back it the college days, grinding on the dance floor was really common. Nowadays, it’s all about twerking.’ To grind also means ‘to work your a*s off’ in order to complete a task. Girl, you haven’t even you started studying to your English exam. It’s on Monday! You’ve got to grind, hun! Be careful about using grind in the UK as we use it to describe a s***l intercourse. Sorry I could not write down all the letters as I got info the content is inappropriate 😅

It’s an erotic dance that high schoolers and people in nightclubs do 😂😂😂

Hey Sophia, Grind is English slang for dirty dancing 🕺.

Hey Sophia. This is a WEIRD sentence lol. To grind in this sentence kind of doesn't make sense in itself (to me anyway.) I'm not sure if they're meaning dancing suggestively with each other, or working on something together. Both uses of the word 'grind' used in this sentence is slang by the way. I'm not surprised it confused you, it confused me and I'm a native speaker :D