。
That really looks delicious.
Literal
Truly delicious-looking.
The auxiliary ~そう attached to the stem of an い-adjective (美味しい → 美味しそう, dropping the final い) expresses a visual or observational 'looks / seems to be.' Distinct from hearsay そう (= 'I heard that...'), which attaches to the plain form — 美味しいそう ('I heard it's delicious'). The copula is dropped entirely here (ellipsis), a common casual shortening. Subject omitted.