what are you … about?
I still didn't understand what you were talking about.
Том даже не знает, о чём вы.
Tom doesn't even know what you're talking about.
Я понимаю, о чём вы меня просите, но я не буду этого делать.
I understand what you're asking me to do, but I won't do it.
О чём вы с ними разговаривали?
What did you talk to them about?
О чём вы, чёрт возьми, думали?
What the hell were you thinking?