A marquee (a tent, in US English; tensostruttura in Italian) is an event structure on poles or frames, with taut fabric panels. It can cover the whole reception or stand ready as a wet weather plan. It is usually hired through the venue or a specialist supplier, not the flower designer.
It changes a lot for the flowers: inside a marquee the light is different and the ceiling can carry a hanging installation, but you need certified rigging points and permission from whoever puts up the structure. The guide on the wet weather plan: flowers, marquees and gazebos explains how to adapt the design; the one on hanging installations covers loads and safety; the one on suppliers who work with your flower designer shows who coordinates whom.
What to ask: who decides whether to put up the marquee and by when, whether the flower designer can hang flowers from it, and how much a last-minute move of the flowers costs.
