Yes, BAR is a Scrabble word!

Letter values in Scrabble US: B 3, A 1, R 1.

Is it a valid word?

BAR is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a room or establishment where alcoholic drinks are served over a counter
a counter where you can obtain food or drink
a rigid piece of metal or wood; usually used as a fastening or obstruction or weapon
musical notation for a repeating pattern of musical beats
an obstruction (usually metal) placed at the top of a goal
the act of preventing
(meteorology) a unit of pressure equal to a million dynes per square centimeter
a submerged (or partly submerged) ridge in a river or along a shore
the body of individuals qualified to practice law in a particular jurisdiction
a narrow marking of a different color or texture from the background
a block of solid substance (such as soap or wax)
a portable .30 caliber automatic rifle operated by gas pressure and fed by cartridges from a magazine; used by United States troops in World War I and in World War II and in the Korean War
a horizontal rod that serves as a support for gymnasts as they perform exercises
a heating element in an electric fire
(law) a railing that encloses the part of the courtroom where the judges and lawyers sit and the case is tried

Also: legal profession, legal community, browning automatic rifle, block off, block up.

Not playable in Scrabble US: GINMILL.