It literally means nothing in the context of Mormonism.
Remember the "witness" Martin Harris.
Poor sap couldn't see the angel and couldn't see the plates. But after many hours of coaching by Joseph Smith, he became a "witness".
In actuality, he was probably hungry and tired and knew that Joseph Smith wouldn't let him go home until he became the witness that Joe wanted him to be. "It is enough! I see it now! Hallelujah!"
And then he went home and had some eggs for supper.
Can you imagine Mormon-style witnesses in the context of real legal/court proceedings?
Martin Harris: No, I didn't see the defendant coming out of the bank with a gun. I didn't see anything.
Prosecutor Joe Smith: Are you sure? He definitely came out of the bank and he was holding a gun. That black pistol...and he had a bag of money in one hand and was wearing a bowler hat. Don't you remember?
MH: Nope. I didn't see anything or anyone at all.
JS: Your honor, I would like to take my witness off to the side to discuss his testimony.
Judge: Sure, why not? What good is a witness that won't testify the way you want him to?
[10 hours later]
JS: So, Mr. Harris, can you tell us what you saw that Tuesday afternoon?
MH: Sure, I saw the defendant coming out of the bank. He had a black pistol in one hand and a bag of money in the other hand. Oh...and he was wearing a bowler cap. I think he also had some snot coming out of his nose and...
JS: Okay, that's enough. No need to get carried away.
MH: But I want to add that he was holding the pistol in his right hand. Yeah, that's it.
JS: No it was his left hand. Remember how I told you that he is left-handed?
MH: Oh, right. Yeah, it was his left hand. I meant to say left hand.
The problem is that when church leadership is pressed on the claims of the church in a forum where there are consequences to lying, they quickly fold. Look at what Joseph F. Smith said at the Reed Smoot hearings. He refused to admit, under oath, that he really was a prophet, only stating that was sustained as such by "his people". He admitted, under oath, that there was no revelation in selecting the leadership of the church. He testified, under oath, that he had never received any revelation.
When Thomas S. Monson was subpoenaed by a UK court to testify of the truthfulness of the claims of the church, during a fraud trial against the church, church attorneys fought against the subpoena and won.
Even when pressed only in the court of public opinion, church leaders avoid and deflect.
Can you imagine how silly the scriptures would look if the supposed prophets in the Bible and Book of Mormon hid behind lawyers, fled to other countries, or issued flat out denials, every time they were confronted about the truthfulness of their claims? Modern church leadership is about as inspiring as art purchased at Wal Mart.