Opened a couple space, for example, I said that only I can see it, can he see it?

If you set this situation so that only you can see it, then no one can see it except yourself. What you sent is that lovers can't see it and others can't see it. But if your friends look at your account. No, but you can tell any other secret. Even if you encrypt it. Or you can look at it yourself? So don't put things you don't want others to see on the internet at any time, which is very unsafe.