The net dollar amount dealers must trade per move to stay hedged; sign tells you the volatility regime.
Gamma exposure (GEX) estimates the total dollar value of the underlying that options market makers must buy or sell to stay delta neutral for a given move. Positive GEX means dealers are long gamma and dampen moves (sell rallies, buy dips); negative GEX means they are short gamma and amplify moves. The magnitude matters as much as the sign — a large positive GEX pins price far more forcefully than a small one.
More terms: Gamma wall · Delta neutral · Gamma · 0DTE options · Dealer hedging · Call wall