What is the red light spinning around on an ambulance called?
What is the sound that comes out of an ambulance to ask people to move out of the way? And the verb that express it, "honk" or "roar" are not the one right?
It is usually a blue light for emergency vehicles in the UK.
Ambulances etc have a revolving light. It is also called a "flashing light"
The sound is a siren.
When you hear a siren or see flashing lights from an ambulance or fire engine, if they are following you, you must slow down and pull over.
I'm not sure what you mean by "verb that expresses it" I suppose an ambulance driver might "turn on" the siren. There doesn't seem to be a particular verb.
You suggest "wail" which is fine as in poetic use. It is an example of personification. It is very good for a piece of creative writing.
Joe raised his collar and walked away from the burning building. In the distance, sirens wailed, and a low moon hung like warning light, red and fearful.
There are plenty of other words that could be used, but none seem specific.
I'll mention, for the sake of completeness, the casual phrase "blues and twos". A police car had "blue lights" and a "two-tone siren" (neeee-naaaa-neeee-naaaa).
The device that actually makes the noise is called a "siren", and we use the same word to denote the sound:
Emergency sirens are distinguishable, so we might refer to "police sirens" or an "ambulance siren". Although modern fire engines also use a siren device, some people do still refer to a fire engine's "bell". Another word sometimes used instead of siren is "klaxon".
There is no word for the sound that comes out of a siren, but sometimes we might imitate the sound phoenetically and make up words like "nee naw".