轮 is very versatile: as a noun it means 'wheel', as a measure word it means 'round' (一轮比赛, one round of competition), and as a verb 轮到 means 'it's someone's turn'.
grammar
轮到 is a very useful pattern: 轮到我了 (it's my turn), 轮到你了 (it's your turn). 轮流 (lúnliú) means 'to take turns'.
