This is the 'Golden Surfer' top from the Zimmermann 2018 ready-to-wear collection.
It has a cream-white base with a yellow/orange/green flower print.
It is long-sleeve (puffy), with an asymmetrical off-the-shoulder fit on one side. V-shaped cleavage in the front and in the back.
It is a size 3 (M-L), but fits size S-M and small L, depending on the fit.
Worn to a wedding, in perfect condition.