A common rule-of-thumb is that any red warning lights are the most urgent. When any of these go off, you should immediately pull over at a safe spot and stop driving. On the other hand, if the light is yellow, that means it is not as urgent. And when a light is green, that indicates the system is working properly.
The most urgent Toyota warning lights are the brake system warning light, the EPS system warning light, the oil pressure warning light, the battery charger warning light, and the airbag warning light.