Yes, it's generally accepted that a glass of water is one cup (8 oz or 1/2 pint).
Many recommend 8 - 8 oz glasses/day. New studies show there's no set amount, but you should drink often enough to prevent dehydration.
By the time most of us "feel" thirsty, we're already starting to dehydrate.
What size is a glass of water is it a half pint ?
No, but it helps. Drinking water keeps you hydrated, which prevents you from retaining fluid.
Drinking a glass of water before a meal can help fill you up, so you won't eat so much.