This means that he was sentenced to serve 3 years, but he will only be required to serve 1 year of his sentence. He will also be on probation for 3 years and if he violates his probation he may have to go back in and serve the remainder of his 3 year sentence. Keep in mind that, depending on what the conviction was for, he most likely he won't have to serve the entire year of his suspended sentence, but that is up to the Department of Corrections.