Guild Wars 2

i am sorry if it was asked before, and forgive me for not getting it, but what exactly means?
lets use 100 hp heal as example so….

so this is what i figured

if i heal alies 100hp with 10% extra now i will heal them 110

or correct me please

will it heal me too or just allies?

Yes it increases your healing effectiveness on other allies/allied npcs . No it does not effect your personal healing.

I guess it’s a chance to ask this question.

What about decimals? Let’s say I heal 105, that would be 115.5, so is that 0.5 just lost?

The game generally rounds numbers. I would hardly consider 1HP any hind of a real loss though.