These are the rose seed pods that form after a flower’s petals fall if the bloom was pollinated. Hips are the fruit produced by rose plants. Apple trees are members of the rosacae family and the apple is a hip. Some varieties such as R.rugosa produce large hips that turn brilliant colors in the fall.
Allowing the hips to develop will cause a rose to slow down or stop producing flowers. It also helps induce dormancy, helping prepare the rose plant for winter in colder climates. In contrast, deadheading will keep the plant from producing hips and encourage it to produce more flowers.