The new errata changes*

"You can't hide from a creature that can see you."

to

Using Ability Scores
Hiding (p. 177).
The DM decides when circumstances are appropriate for hiding. Also, the question isn’t whether a creature can see you when you’re hiding. The question is whether it can see you clearly.

Which effectively changes the line on 177 to

"You can't hide from a creature that can see you clearly."

With the errata there are no contradictions.

Lets go through this step by step.

On page 177, you can attempt to hide if nobody can see you clearly. Which means you can be seen, before you attempt to hide.

On page 192, it then says that when you hide, you gain the benefits of being unseen. (As listed in the section titled: Unseen Attackers and Targets) That means that when hidden, those who have a lower passive perception check than your stealth roll, can't see you. (Or those who try to search for you and fail) There are no benefits to being hidden other than becoming Unseen. Being Unseen, provides a few benefits.

On page 195, it then lists the benefit of being unseen by those who were unable to detect you, and that is that you can now attack them with advantage.

There are no contradictions.

"if you come out of hiding and approach a creature" refers to moving out in the open, where you can be seen clearly, as stated earlier in the rules:

You can’t hide from a creature that can see you clearly...

5e rules designer Jeremy Crawford has also confirmed this:

You can attack while hidden and gain the benefit. But if you run out into the open and then attack, you're not hidden when you attack.

However, as implied by the rules and his tweet, as long as you don't fully expose yourself, you can peek out from whatever you're hiding behind to make an attack.

Shooting from cover and running out into the open aren't the same thing.

It's also worth pointing out that hiding in combat imposes no limitations on your movement speed. This is a common point of confusion because of the Travel Pace rules.

Stealth imposes no movement reduction in combat.

In short, as long as you stay out of sight and don't do anything noisy, you'll remain hidden until an enemy moves into a position where you can be seen clearly, or uses the Search action and succeeds on an active Perception check to find you.

Jeremy talks about Stealth and Hiding at length in this episode of Dragon Talk. Besides touching upon some of these points, he also explains that the hiding rules are deliberately open-ended because there are too many circumstances that could influence whether you can get away with being sneaky. Rather than limit players to a set of rules that's too rigid or naive, or bogging down the game with excessively complex hiding rules, they left it up to the DM to make exceptions as needed and work with the players rather than against them.

With all that said, there is one action that's not explicitly called out in the rules but will most likely expose you: casting a spell with a V component. From the rules:

The words themselves aren’t the source of the spell’s power; rather, the particular combination of sounds, with specific pitch and resonance, sets the threads of magic in motion.

When asked how loud the V components need to be, Jeremy said this:

The verbal component of a spell must be audible to work. How loud is audible? That's up to the DM.

Although the level of loudness is left up to the DM, "audible" by definition means it can be heard.