In the preschool years they also develop metalinguistic awareness the ability to treat language as an object separate from the meaning it conveys. Three years old children can tell because it doesn’t make sense. They may show that they know it's a bit odd, but they will focus mainly on the fact that they can understand what it means. Five years old on the other hand know that is wrong in a different way from they can tell you but the other is the wrong way around.
being able to define a word, or to say what sounds make up that word.