If a book on your wishlist is on hold, can the public still see that book? Or is it only visible to other people once the hold is off?

It's only visible to the person to whom it's been offered.

I meant if someone was to go look at your whole WL.  The books that you have put on hold for whatever reason, can the person who is looking at your WL see the books on hold too?

Oh sorry, I misread and thought you had posted the book and it was on hold for another member.

No, the books that are on your wish list which are on hold are invisible to other members. You can verify this by putting some books on hold and then going to your My Account page. There's a My Profile button on the right just below the Need Help link. Click that and then select the Wish List tab. That's how your wish list looks to everyone else.

Thank you!  That's exactly what I wanted to know.