LogFAQs > #978752496

It means multiple things depending on who says it.
For some it means no minorities, no women (unless they are nude and objects), no messages, do not touch "liberal" subjects unless it's mockery.

For others it means they don't mind such things but they want it to be done well and not some awkward hamfisted message where characters only exist to deliver a statement of the developer or writers, where they may as well look directly into the camera to lecture the player on whatever.

There are other meanings too but those are the two biggest in my opinion.