Musical aptitude is like being really good at understanding and making music. It's like being a great artist who can paint beautiful pictures or an amazing athlete who can run super fast.
Some people are born with a really good musical aptitude, while others have to work really hard to develop it. It's kind of like how some people are born with naturally curly hair or blue eyes, but other people have to use products or wear glasses to make their hair curly or correct their eyesight.
Musical aptitude can involve things like being able to hear different notes and tones in music, understanding rhythms and beats, and being able to read and play music on an instrument.
If someone has a good musical aptitude, it means they might be able to learn and play instruments really well or sing in a way that sounds really good. But even if someone doesn't have a natural musical aptitude, they can still learn to appreciate and enjoy music by listening to it and practicing playing it.