Expressive means showing feeling clearly. A face you can read across a room.
Faces, eyes, hands and music are the usual subjects, and an expressive performance is one that carries emotion rather than just notes. Applied to a person it is a compliment about openness. Language teaching uses the word technically, since expressive language is what a learner can produce as opposed to what they understand. Its opposite, inexpressive, describes a face that gives nothing away, and deadpan is the deliberate version of that.
1adjectiveexpressiveClearly showing thoughts or feelings.
“She has enormously expressive hands.”
Middle French
expressif
English, today
expressive
From Middle French expressif.
Etymology from Wiktionary, CC BY-SA