Hello,
When i set up a game, what does mean "Increment in seconds" ?
Thank you
Jerome

It's the amount of seconds you gain for every move you play. The same also happens with the opponent's time for every move he makes.

@Jerome , well here is your Answer:

Yes, @Nihongo-sanni is right.
It means that if you play 5+3 Blitz Game, it means after each move, you get 3 seconds extra time. Same happens with 3+2 and 2+1 where 2 seconds and 1 second are incremented respectively. Actually increment gives you more extra time, when you premove, especially in ¼+1 games.

thank you for your answer.
It's a cool feature !
Have a nice day