In the first photograph, you must drive lesser than 50 km/h
In the second one, if the light is red, you have to stop. If the light's orange, you can pass but carefully and if it's green you can pass.
And in the third one you have to be careful because that sign means that there's a school nearby.
Explain in your own words what you have to do, or what each of these markings or signs indicates.