It’s actually piss easy lol. 4 is harder and 5 is really hard. Mostly people just learn tricks with 4 balls. All you gotta do is hold 2 balls in one hand and one in the other (for the sake of the example I’ll assume you hold 2 balls in your left and 1 in your right). Then throw one of the two balls in your left hand up and diagonally right to the other hand. Then when that ball reaches its maximum height throw the ball in your right hand up and diagonally left to the left hand. Try and catch them both and practice this until you get the hang of it. Then add in the third ball when the second ball reaches its maximum height and just repeat the process. Once you know how it works it’s very easy, you will just struggle with consistency until you’ve practiced enough and can catch the balls better and throw them less randomly