Hi, It is an interesting question, and thank you for bringing this up! As a bilingual speaker, I grow up learning both Chinese and English, and I totally understand that there are so many unnecessary verbs in Chinese if you understand in the English mindset. Sometimes you have to change the way of thinking into Chinese to understand the language, and I know it's very challenging, I was struggling to learn both languages too.
Let's try to divide the sentence into parts:
- 你 you 是 are 在说 saying.... (You're trying say ....)
if I directly translate the sentence into English, there is no actual word means "trying", so 是 is a verb, could be understood as "are",
but the sentence could be shorten as "你 you 是 are 在说 saying", if there is no 在 in this sentence, it still means the same thing, but there is no emphasis on that you are saying in the present.
also the sentence could be shorten as "你 you 是 are 在说 are saying", if there is no 是 in it, it also has the same meaning (you're saying), but 在说 could be understood as a verb together means, saying at this moment.
- 我 I 不是 don't 很 very 懂 understand 你的意思 your meaning。 (I don't really get what you mean.)
this sentence is a little different from the last one, you can take 不是 as the don't in English, and the actual verb is " 懂 understand" , but this is negative sentence, so we have to add "不是 don't";
but if this is a affirmative sentence, such as "我 I (是 do) 很 very 懂 understand 你的意思 your meaning", it works the same way as English, "是 do" normally can be eliminated, and "懂 understand" is the only verb, but "是 do" can be added when you want to emphasize the fact that you understand the meaning.
Chinese grammar is not easy and quite confusing, hope this could help! If you have any further questions, please feel free to take my lessons and I will be beyond happy to help!