What is the meaning of Rear_admiral_(upper_half)?

A flag officer in the United States Navy, United States Coast Guard, National Oceanic and Atmospheric Administration Commissioned Corps, or Public Health Service Commissioned Corps of a grade superior to a rear admiral (lower half) and junior to a vice admiral. A rear admiral (upper half) is equal in grade or rank to an Army, Marine Corps, or Air Force major general. A rear admiral (upper half) wears a two star insignia on most uniforms and a gold stripe above a broad gold stripe on the sleeve of certain dress uniforms.

A naval officer of equivalent grade or rank in the navy of other countries.

Source: wiktionary.org