"The road ahead is bumpy". It's as true of driving as it is of life. Bumps can be due to hot / cold weather, heavy traffic, tree roots, or put there deliberately.
But "speed bumps" are where the road level is artificially changed to calm traffic. They're marked by a white triangle on their leading slope. They can be:
Approach bumps with as much speed as feels comfortable (for you and your passengers). And definitely not so much that your tyres leave the road when you descend the other side !