Oh, OK I'll go on. You know what a flower petal is. You may have noticed that sometimes behind the petals there are little green things. Those are sepals (or the calyx).
Actually in some plants there are no petals, just sepals which look like petals but don't worry about that.
In other plants there are both petals and sepals but they all look like petals and it's impossible to tell petals from sepals. In this case all the pretty bits are called tepals to, you know, make things easier.