The last song of the Musical. It ties up after, what I assume, with Luke trying to kill Percy and Percy surviving.
This is all foreshadowing the last book in the first Percy Jackson series, The Last Olympian. Specifically The Battle of Manahetten is on the horizon but the demigods have a lot to work to do until then.
It’s reassurance to the audience that the demigods are doing the best they can and dealing with their godly and mortal problems and will ‘be back next summer’ aka, surviving.