Why do you understand every word, but you don't understand what you are saying?

Hello, I think there are about three possibilities.

1. The words in the sentence have other meanings, but we don't know in advance, so we can't understand the meaning of the sentence.

2. Wrong understanding of sentence grammatical structure and wrong division of sentence components. For example, I read an English joke. "Holding a pig with one hand" can be understood as "holding a pig with one hand" or "holding a pig with one leg". This is the difference caused by different understanding of sentence grammatical structure.

If you haven't read enough English, even if you can grasp the meaning of each word and understand the grammar of the sentence, you may still not know what the sentence is saying. Because Chinese and English have different expressions and thinking habits.