The DXY measures how strong the US dollar is compared to 6 major currencies (euro, yen, pound, and others). Think of it as a 'dollar thermometer' — when it goes up, the dollar is getting stronger.
How does it affect gold?
Strong dollar → gold gets more expensive for buyers in other countries → fewer buyers → gold price drops.
Weak dollar → gold gets cheaper internationally → more buyers → gold price rises.
Simple rule: DXY up = bad for gold. DXY down = good for gold.