The group is made up mostly of retired people and children. Ladies are dancing together, possibly for lack of male partners. Perhaps because it's daytime on a workday. Not enough people are dancing, anyway, for it to be a formal occasion. It looks improvised.

There's a fountain to the left, drops are falling. The place looks public, a park or garden, perhaps of a palace or "stately home". It looks French to me, but there's no clincher.

So. An afternoon concert somewhere in a French public garden attracts older folk for the dancing and mothers with their kids?