... all the traffic lights seemed to turn red for ten minutes
This one feels off.
"Turning", in this context means a change in state. The change is quick, especially when compared to the mentioned 10 minutes. The entire interval that is being addressed here consists of two separate/separable components: 1.) a light turns red, 2.) it stays like ...
In US English at least, "what you mean?", used as a stand-alone question is non-standard, but is a feature of some dialects, particularly low-income inner-city dialects, mostly as spoken by Black americans. Some people will look down on those who talk in this way. If a person, who does not come from a group that uses this pattern, adopts it, they ...
They're used differently, e.g.:
What do you mean by "tall"?
This calls into question how "tall" is used in this context, for example, "The Matterhorn is tall." Compared to K2 Compared to Ben Nevis?
Be sure to say what you mean.
In this usage, it calls into question the person said what was intended.
"What you mean?"...