Answer:
Generative property.
Explanation:
The generative property of language explains how, out of finite words and linguistic resources we are able to create new phrases and new meanings. It explains how, out of a finite quantity of words and structures in our heads we are able to rearrange them to form new ones that we haven't heard before.
This is why Timmy has, most likely, been the first to said those words in that exact order and meaning.