A creature is Hiding by taking the Hide action.
The rules on unseen attackers and targets state:
When you attack a target that you can't see, you have disadvantage on the attack roll. This is true whether you're [A] guessing the target's location or you're targeting a creature you can hear but not see. If the target isn't in the location you targeted, you automatically miss, but the DM typically just says that the attack missed, not whether you guessed the target's location correctly.
When a creature can't see you, you have advantage on attack rolls against it. If you are hidden–both unseen and unheard–when you make an attack, [B] you give away your location when the attack hits or misses.
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Does [B] "you give away your location" refer only to [A] "guessing the target's location" — in other words, the location no longer needs to be guessed so there is no miss chance. Are there additional implications of having your location given away?
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If the Hidden creature changes location is their new location also given away?
@MarkWells rephrased the question as "If you are hiding somewhere where you can't be seen, and you attack, are others now able to see you, or can they just infer your location?"
Note: A lot of people are saying that the benefit of Hiding is that your location is unknown, that if your location becomes known then you stop hiding. If someone has anything in the rules to support this position I would love to see some quotes. From what I have read the benefit of Hiding is that the character is unseen and unheard, and enemies need to pass a Perception check to detect the character. The only benefit of having an unknown location that I found is enemies have to guess the character's location, and the only disadvantage of having a known location is the removal of this bonus.
I would prefer answers regarding RAW supported by quotes from the rules.
Best Answer
"Giving away your location" just means that enemies know where you are. It doesn't necessarily mean they can see you.
For example, you can be invisible but, due to drastically failing a Stealth check by sneezing, the enemy now knows there is an invisible creature standing somewhere by the bookshelf. Thus giving them something to aim at (despite not knowing the exact disposition of your body or whether you are armored or holding a shield or weapon etc).
If you were hiding using conventional means (say, in a shadow behind a wall) and then jump out and attack then enemies will now know your location and will be able to see you. Unless you duck back behind the wall of course, but even then they will know you are lurking around somewhere nearby. If you are a rogue you would get sneak attack on that first attack, but possibly not subsequently since enemies know you are around and will be on the look out. (The DM may allow you to make another Hide check to fool your opponents).
Regardless, your location has been given away and an enemy may just decide to walk around the wall to hit you.
If you are invisible and start without the enemy knowing you are there thanks to a successful Hide check - and let's say its Greater Invisibility, so attacking doesn't break the invisibility - then attacking "gives away your location" because, again, enemies know you are around and roughly where you are. You may be invisible, but if the enemy suddenly finds themselves with an arrow sticking out then they will know somebody is about ("the arrow came from over by that tree!").
You are still invisible so enemies attack with disadvantage, but they know roughly were to aim at unless you move. If you do move then the DM may require further Stealth and/or Hide checks to avoid the enemy being able to pinpoint your location now that they know an invisible enemy is around (whereupon, if they fail a Perception check, they will just have to guess your location and any attack may just miss anyway as per the rule you quoted).