How do I translate these verbs?
"你为什么不走过来?" --> 你(you) 为什么(why) 不走过来(don't come over) --> "Why you don't come over?"
"你为什么不说出来" --> 你(you) 为什么(why) 不说出来 (not speak out) --> "Why you don't say it?"
"为什么不肯说" --> 为什么(why) 不肯说 (unwilling to say) --> Why do you  unwilling to say?"



  What exactly does 走过来, or 说出来, or 肯说 mean?


'走过来'  means 'come over (by foot)'  

'说出来' means 'speak (it) out' = "say it"

'肯说' means 'willing to speak/ say'

Depend on context 肯 could mean 'willing to' or 'agree to'

In English, you must put the question form before the subject. For example, you can't say "you why don't come over?" instead of  " why you don't come over?"

However, in Chinese, question form and the subject can switch place.  e.g. "(你)为什么不走过来?" = "为什么(你)不走过来?"