Sweep..

Hi ladies! What is a sweep? And can I just ask to have one done? Im in the UK (not sure if UK/U.S. are different). I seen a friend in town earlier and she asked if I had arranged to have a sweep done. More info on what they are and how to go about getting one etc would be great! I'm currently 36+5 weeks pregnant and a FTM & feel as if I'm asking a question that I should know the answer too! 😩😂 thank you in advance for replies! 🌻