In plain English
Less grip ahead — maybe mud, ice, or a polished surface. Slow down gently and keep your steering and braking smooth. No sudden anything.
Where you'll see it
Near farms, on shaded country bends that ice over, and on roads that get greasy after rain.
The common trap
Reacting by braking hard — which is exactly how skids start. The sign is asking for gentleness, not panic.
Memory anchor
The little car is dancing — wheels one way, body another. Smooth inputs stop the dance.