Attack of creature with many limbs

[Koraxs]

Hello. Help me please to understand how many attacks can do creatures with many limbs for standart action.
I сan't understand about Hydra(((
It is rule that if you want to do more then one attack in round it must be full-round action
But in description Hydra melee attack I see "5 heads" so RAW it is 5 heads-in-one attack /thats like in cartoons, but I have in my mind thats mechanically it no so/

So how attack Hydra (if you please compared Hydra attack/*action with girallon)???

[Belafon]

As a standard action you can make one and only one attack.

If a creature has multiple natural attacks (like five bites), it can choose any ONE of those attacks to make as a standard action. In a full-attack, the creature can attack with all its natural attacks.

[Derklord]

Koraxs wrote:

But in description Hydra melee attack I see "5 heads" so RAW it is 5 heads-in-one attack /thats like in cartoons

No, it's not. What you describe does exist, best examplified with the Decapus which has ten tentacles, but using them works as a single attack. Notice that the tentacles do not have a number leadign the word in the attack section - that's because a leading number indicates multiple individual attacks.
Indeed, if a hydra would make all the bites as one attack, it would only have a single attack per round, and thus be much weaker.

In general, an attack is one attack roll, and if successful, one damage roll. How many body parts move as part of the attack is irrelevant. A hydra's bite's damage roll is 1d8+3, so when using e.g. the attack action, the hydra can't deal more than 1d8+3 damage with that action.