This is the 11708th most frequent French word.
serlorsque
It seems "serlorsque" is a typo; the correct word is likely "lorsque," which means "when" or "while" in English.
Used as a temporal conjunction to indicate the moment when something happens.
Lorsque je suis arrivé, il pleuvait.
When I arrived, it was raining.
Indicates a point in time in the future when an event will occur.
Nous irons au parc lorsque le soleil se lèvera.
We will go to the park when the sun rises.
Introduces a condition during which the second clause is true.