Hey buddy, do you know when you learn something new, like how to add two numbers together, and then you use that knowledge to solve more difficult math problems, like adding three or four numbers together?
Well, in a similar way, when we create a sentence, we start with a small part, like a subject and a verb, and then we add more words to make a complete sentence. Syntactic closure is when we keep adding more and more words to a sentence until it is complete and can stand on its own.
It's like building a tower with blocks. We start with a base block and keep adding more blocks to make it taller and sturdier. Only when we have added enough blocks to make the tower stand on its own, we can say that we have achieved syntactic closure.
So, in short, syntactic closure is when we add more and more words to a sentence until it is complete and can stand on its own, like building a tower with blocks.