Tolsimir Wolfblood has two abilities which each grant creatures of the appropraite color +1/+1. A creature that meets both requirements, like Rhys the Redeemed , will get +2/+2.
I have Tolsimir Wolfblood on the field and Rhys, the Redeemed
Does Rhys get +1/1 or +2/2?
It is green and it is white, so it gets both bonuses.
Actually, the issue doesn't lie in Rhys's coulours but in the fact that Tolsimir has two separate abilities, if it were worded like this, Rhys wouldn't get +2/+2 but +1/+1: Green and white creatures you control get +1/+1.
Rules question? Have you read the Basic rulebook already? No? Why not take some time to do that?
How to autocard (do this to specify a card in your posts): Type [c]Black Lotus[/c] to get Black Lotus . Type [c=Black Lotus]The Overpowered One[/c] to get The Overpowered One .