Meaning of 'you understand' in the context

Question

I know the literal meaning of 'you understand', but this sentence in the context below seems to have another meaning. Here is the example, which is from a novel 'Baker's blue-jay yarn' by Mark Twain.

It was a knothole in the roof. He cocked his head to one side, shut one eye and put the other one to the hole, like a 'possum looking down a jug; then he glanced up with his bright eyes, gave a wink or two with his wings - which signifies gratification, you understand - and says, 'It looks like a hole, it's located like a hole - blamed if I don't believe it is a hole!'

Answer 1

"You understand" is commonly included as an interjection. Literally it means that the speaker is asking the audience for confirmation that they understood what was meant. However, it has a lot of idiomatic uses.

For instance, someone might quickly go through details of complex quantum physics, and then follow up with "you understand". There is is meant ironically, because the speaker is well aware that what they said was very hard to follow.

It is also used when someone is explaining their motives, and is seeking sympathy. "He was sleeping with my wife, so I had to kill him, you understand."

In this case, it is being used to draw attention to the fact that the phrase before it was an innuendo and not to be taken literally. It is also sometimes used humorously in this context if the preceding innuendo was very obvious. By pointing it out when it is already obvious, it makes the speaker sound humorously foolish, patronizing or overzealous.