You can arrive to the US as many times as you wish within the ten years but the actual entry grant will be given by the CBP officer. After a few questions, the officer will stamp your passport with an amount of time (usually 6 months). This determines how long you can stay in the US during this time. Should you leave the US, that stamp duration is automatically ended and you can go anywhere for as long as you want and come back to the US and get stamped again. Of course, as long as it is within the 10 year period of the visa.
Just remember that having the visa is not a guarantee of being allowed entry. It hardly ever happens but technically a CBP officer can deny you entry.
More info here: