Here's why:
* Grammar is about structure, not meaning: Grammar focuses on the arrangement of words and their relationships within a sentence. It's about how words are put together, not necessarily what they mean.
* Nonsense words can fit grammatical rules: We can create nonsense words that fit the grammatical categories of nouns, verbs, adjectives, etc. Even without actual meaning, these words can be arranged in a way that follows the rules of the language.
Example:
"The blimp floogled the flibberty gloob. "
This sentence uses nonsense words, but it has a grammatical structure that makes sense:
* The (article) blimp (noun) floogled (verb) the (article) flibberty (adjective) gloob (noun).
Even though we don't know what "blimps," "floogled," "flibberty," or "gloobs" are, we can understand the sentence's basic structure and how the words relate to each other.
Important Note: While a sentence with nonsense words can have grammatical meaning, it won't have *semantic* meaning (actual, understandable meaning). It will sound like a sentence, but won't make sense in the real world.