It is a black, American Eagle Outfitters, size XS, spaghetti-strap crop top featuring a smocked bust, made of 100% viscose.

Fabric and Detail: The top features a wide band of smocking (elasticized gathering) across the front/chest area, providing a snug and comfortable fit. The main body of the top appears to be made of a lightweight, soft fabric.
One of the tags indicates the composition is 100% Viscose (excluding the elastic). Viscose is a type of rayon, known for its soft, flowy drape.
Brand and Sizing:
Brand: American Eagle Outfitters.
Size: XS (Extra Small)
Origin: The garment was Made in India (FABRIQUE EN INDE / HECHO EN INDIA).