It's really not. So a tree has branches right, they split from the main trunk. Same with betta's, they have a main "Trunk" and then you get branches from there. Those branches can branch off again and again and again. Ray's are like the twigs, they're the ends of the branches so you count those to get a "ray count" like the picture I posted up there that I couldn't figure out how to delete after I edited my post lol. Those four numbers are ray's, the little twigs at the end of the branch.
Does that make more sense?
Rembrandt II, Suiché
Leopards: 1:4 Hawkeye, Luna, Astrael, Dorian, Cullen
Gargoyle: Cloudjumper and Toothless