Hello! I'm new to the black butler fandom and I wanted to know how many seasons there are? And also does ceil really die in episode 24?
Welcome to the fandom, I hope you are enjoying yourself. The anime can be a little confusing but I will attempt to clarify it all for you.
Spoilers ahead, obviously.
Season one followed the manga fairly faithfully (with some filler) up to a point (after the curry arc) and then split off to a totally different story that was written for the anime. In that season Ciel was implied to fulfil the contract and give his soul to Sebastian and whatever that might entail is left up to the viewer.
Season two picks it up later and is… convoluted. It has a different tone and pace than season one and starts in a very jarring way. The story has some interesting points in it and some people really like it but It’s not my cup of tea. In season two though, Ciel is alive and how that happens is a question that is (sort of) answered in the story.
Book of Circus came out recently and picked up from where the anime stopped following the manga in season one. It’s very well done and sticks faithfully to the story.
Book of Murder is a two episode OVA that follows the next manga arc and is the last animated Kuro adaptation we have received. The manga goes on for three or four more arcs and is still running but no more anime has been announced currently.