Okay kiddo, do you remember seeing lizards or snakes before? They are called reptiles and they have some unique features like scales on their body, cold-bloodedness, and laying eggs.
Now, imagine if there was a type of creature that looked kind of like a human but also had some features of a reptile. This is what we call a reptilian humanoid.
They might have scales on their skin or even a tail like a lizard. They might also have eyes that look like a snake's or even some sharp teeth like a crocodile!
But don't worry, they're not real, just a cool idea that people like to imagine in stories and movies. They're not something that you're likely to see in real life.
So, there you have it, a reptilian humanoid is a made-up creature that has some features of a reptile and some features of a human.