It is a Canna, no idea what variety but looks similar to the types you most often see at the GC in early summer. It doesn't look dissimilar to 'Alberich'Canna Sale Catalogue (hartcanna.co.uk)
Plant it in a bigger container, feed and water generously, and it will flower for a long time. I have no room to store these overwinter so can't grow them now, but they are lovely. Check out the 'Canova' series, which are various kinds of pink.