Okay kiddo, do you know what an album is? It's like a bunch of songs that a singer or a band puts together and releases all at once. Normally, people know when an album is being released because the singer or the band tells them ahead of time.
But sometimes, a singer or a band decides to release an album out of nowhere! That's called a surprise album. It's a surprise because nobody knew it was coming until it was actually released.
It's kind of like if your favorite ice cream place suddenly opened up a new location right down the street from your house without telling you - it would be a SURPRISE!
Sometimes, surprise albums can be really exciting because fans get to hear new music without any warning. Other times, people might not even know that the surprise album exists because they weren't expecting it.
Does that make sense, little one?