During the early 19th century, gently-bred maidens were closely chaperoned. This didn’t mean they had no chance for private conversations with gentlemen, but the opportunities were extremely limited. Dancing was one method.
About halfway through this video clip is a fine example of a private conversation in a crowd. (It continues in Episode 2 Part 5/6.)
Every time I watch this (and yes, it’s been many times), I marvel at Darcy and Elizabeth’s being able to talk while not missing their steps—and this was only one of many dances they would have to know.
And what, exactly, were the dances? You’ll find the answers here at Regency Dances Org.