Can someone explain the dye thing to me?

I'm a little prince moth and I stopped playing regularly once aviary ended, only logging in then and there to check in for a few mins, and I'm curious now since I'm still seeing posts from here and wanna play again, but I know it'll be very confusing with all the new stuff that dropped, so can someone explain it to me like I'm 5? I know there's dyes you can find, but can you dye any item or are there limitations? Tank you