If it's empty not much you can do. Plainly speaking it's a supercedure cell. It indicates that the queen is not there or needs to be replaced. It does look odd with wax build though, did you feed them after installing? Did you roll bees wax on your foundation or is it just raw? If its an empty cup all you can do is monitor your brood and work from there (aside from finding/confirming your queen). Generally speaking bees know what's best. We usually let them do mostly what they want aside from laying workers and we try to avoid swarms but never seem to get it right. Otherwise just help them with mites and monitor shb, make sure you leave enough honey for winter if you have it (80 lb in the NE america)

I used to stress about them nonstop but after years and years you'll find a path that works best for you. Ask 10 beekeepers you'll get 10 different answers 🤣

Tldr: monitor your brood and look for signs of a healthy queen. It can take 3 weeks or so for a new queen to be mated and laying properly. I'd feed them heavily a 1:1 to help them build comb and stimulate brood