Bench in legal contexts means simply the location in a courtroom where a judge sits. The historical roots of that meaning come from judges formerly having sat on long seats or benches (freestanding or against a wall) when presiding over a court. In modern courtrooms, the bench is usually an elevated desk area that allows a judge to view the entire courtroom.
The word also has a broader meaning in the law – the term "bench" is a metonym used to describe members of the judiciary collectively, or the judges of a particular court, such as the Queen's Bench or the Common Bench in England and Wales, or the federal bench in the United States. The term is also used when all the judges of a certain court sit together to decide a case, as in the phrase "before the full bench" (also called "en banc"). Additionally, the term is used to differentiate judges ("the bench") from attorneys or barristers ("the bar"). The phrase "bench and bar" denotes all judges and lawyers collectively.