Deadheading is the removal of finished blooms to encourage further blooms and improve the appearance and shape of the rose. You should deadhead repeat-flowering shrub roses and once-flowering shrub roses that don’t produce hips. Do not deadhead hip-producing roses if you want hips in the autumn/winter.
There are two stages to deadheading. The first is mainly aesthetic, removing the brown finished blooms so you can enjoy the remaining flowers without interruption. The second stage encourages new blooms and helps to maintain a compact shape.