What is the meaning of Warrant_officer_class_2?

NATO rank OR-8 in all British armed services.

A warrant officer in the British Army ranking above staff sergeant and below warrant officer class 1; company sergeant major

A warrant officer in the Royal Marines ranking above colour sergeant and below warrant officer class 1.

A warrant officer in the Royal Navy ranking above chief petty officer and below warrant officer class 1.

A warrant officer in the Australian Army, ranking above sergeant and below warrant officer class 1.

Source: wiktionary.org