EQ is such a big field, it's hard to find an exact use for it on every type of music. What needs to be understood in basic is that in all music you usually divide the EQ up in 3 big parts: You have
Low,
Mid (mostly categorized in low-mid and hi-mid), and then you have
High. These sort of represent the type of sound in that part of the EQ:
Low: This is all about BASS right here, if you are looking for bass you WILL find it here

and who doesn't love bass right? Kick drum as well ofc... everything that goes BOOOOM!
Mid: This part is about a LOT of stuff... but I think I can sort of nail it down to two big areas. You got percussive sounds, sort of the hit in all percussive sounds here.
Snare for example fills up a big part of the mid. And then you have "melodic" sounds. Imagine the melodies in a song, those are found in the Mid. Vocals, guitar and horns fill up this part.
High: This is all about "Ssssss". The highest frequencies are important to get a sense of clarity and closeness to the sound. Cymbals, hi-hats, sweeps all fill up this part. SsSsSSsssss
I can give you some advice with the EQ for producing hip hop to get started:
Say you have sampled a track where you really dig the bass line... but SH!T there's a hi-hat on the track at the same time that you don't want because you already have a hi-hat on a drum track. Hey no problem! Just put an EQ on the sample, change the freq on the High parameter to like 1k-2k Hz, and then push the gain down. Now you should start having a bass line without the hi-hat.

Say you have sampled a drum break, but since it's "just" soul it doesn't bang hard enough. What you might need then is to boost the kick and the snare. So the kick is in the Low section sort of like 200 Hz and below, gain it up and you should hear the boom coming out a lot more. For the snare, this is a little bit harder since different tracks have different snares that sounds different. However you usually find some "crack" in the snare at around 1.5-3 kHz. Try to gain it and see if it brings out the snare.

That's all for now, ask if you want some more advice. I also want to add that producers like Dr Dre doesn't have real hard ass bangin drums because he
boosts the f*ck out of him drums. Dr Dre is a delicate chef! He carefully work his EQ to find the right frequencies to gain and lower. Think of it like spices, too much salt? nah I don't dig that. Not enough pepper? let's boost that.
It's a long post but I hope it helps =)