In Protection From Poison 5e spell you touch a creature. But if it is poisoned, you actually neutralize the poison. Suppose, if more than a poison afflicts the target and also you neutralize on the poison which you know has been present or else you neutralize one at random.
Actually, for the specific duration, the target has an advantage on saving throws which are against being poisoned and it also has resistance for poison damage.
Attributes Of d&d 5e Protection From Poison
|Casting Time||1 action|
|Classes||Cleric, Druid, Paladin, Ranger|
|Name||Protection from Poison|