The number indicates the amount of life points recovered after each round.

ya me and some friends found out but still they need to fix the warding on it

you too.. *wording

This group skill is really small life gain, but if you got chars, like Azure Fang or 1 of the Tsunade's which increase total healing by x%, this stat is gonna work with it.
Also when the Chakra system comes, it will exist a chakra for this stat, which gives a much bigger amount, than the group talent. :P

What are u guys talking about? U mean leech?

no there is a group skill called life gained

So how can i have leech?

its increases leech

lightning mains and guy has skills that give give leach

this skill is worth upgrading for the future

I believe when you reach higher levels, the life recovery isn't high enough to matter anymore. though it would be a make-or-break situation if the opponent were evenly matched, i think using it in the inner gates isn't worth it. I'd rather go for Damage Reduction or Critical.

I don't know if it increase leech, but it certainly increase the healing you get at either the start or end of each round. This isn't very useful NORMALLY, because except for earth, it rarely gets more than 5 rounds, and at that regen only works if your char is damaged, and usually a char isn't damaged or go from damaged to dead within 2 rounds, so that's how much hp you'd get, 2x of the value.
That said, this is very valuable for survival trial, especially if you are not using good healers. You can sometimes kill all enemy except those that can't really hurt you and then drag it out (works best if you can generate clone/shield to absorb new damage or if enemy doesn't attack at all), this way, your char will regen to be in a better state for the next fight.