Pushing and pulling helps your baby to develop their awareness of their body as these movements result in sensory information from their joints, as well as information from what they touch and see.
It is probably good to be aware of this interest and have a bit of safety check in the areas where your baby plays. They might be interested in pushing and pulling but not aware of the risks that pushing some objects might bring, but if you are happy that what they are pushing or pulling is safe then this is a great way for them to learn about their body.