Potential for value identification

In the SD
Hello,
A. I wanted to ask, a somewhat strange question, if a person is able to understand the phrase "life has meaning," but on the other hand, consciously does not believe that life has meaning, is it still possible to say that following the ability to understand this concept on the potential level, this does show that he believes that objective meaning exists in one way or another?
Because if he believes that there is absolutely no meaning, this concept would be complete gibberish for him, wouldn't it? For example, can you understand a person who talks about the feeling of a turtle when it sees the sea? Or of an alien from another planet, certainly not. So it seems inappropriate to talk about understanding a concept when he categorically denies it.
on. And I wanted to ask the same question about all values. For example, if a person fully understands the claim that helping others is a good deed and is able to argue with people who have objective morality, but on the other hand consciously thinks that there is no such thing as "good" at all, isn't there some kind of problem with such a debate, which was supposedly supposed to be a discourse of the deaf according to him?