You know how we have different seasons throughout the year? Well, there are two special days when the sun lines up exactly with a really big, old building called Angkor Wat in Cambodia. This alignment happens during the equinoxes, which are the times when day and night are almost the same length all over the world.
Now, Angkor Wat is a very special place because it was built a long, long time ago by people who didn't have fancy tools like we do today. They were very clever and built it in a way that the sun would align with it during the equinoxes. This means that on those two special days, the sun rises up from behind Angkor Wat and looks really beautiful. People come from all over the world to see this special event!
So, to sum it up, the Angkor Wat equinox is when the sun lines up perfectly with a big, old building called Angkor Wat and makes a really pretty picture when it rises up on two special days each year.