What do green signs with white lettering generally provide?

Green signs with white lettering are guide signs. They provide directional and informational guidance — route numbers, destinations, distances, exit information, and street names — helping drivers navigate. Green is the standard color for this 'where you are going' information on highways and roads. Other guide colors include blue (services like food, gas, lodging, and hospitals) and brown (recreational and cultural points of interest). Distinguishing guide signs (green/blue/brown, informational) from regulatory signs (laws you must obey) and warning signs (yellow/orange hazards) is part of understanding the road-sign system.