"What does this character mean?"
The 是 seems unnatural. Shouldn't it be 有? That's how I ask my Chinese teacher irl.
"意思" translates to "meaning." It confused me how it was ever used as a verb because the sample sentences don't seem to use it as a verb. And after talking to my Chinese friend, he told me it is not a verb in Chinese.
So, the sentence roughly translates to "this character/word IS what meaning?" ==> "what is the meaning of this character?", which is kind of weird and now I understand why the commentators above think that 有 should replace 是. Then, it will translate into "this character HAS what meaning?" From there, the more natural english expression is "what does this word mean?"
He told me it is also grammatically correct to write "this character's meaning is what" --> "这个字的意思是什么" From the word bank they give, there is no "的" so you can only write "这个字是什么意思"