This is a stretchy cowl neck, long top/dress (around 100cm).
No tag so would guess-timate about a size 20? Colours in photos may be deceiving as photography's not my thing, but black, white, charcoal, and grey.

3/4 sleeves and bodice insert are plain black stretchy t-shirt type material, cotton elastane maybe? Bodice insert has three plain black buttons for decoration.

Easy throw-on top with low cowl-type pockets.