what's

英 [wɒts]

美 [hwɑts]

是什么;什么是;什麽;what is 或 what has 的常用口语形式，尤当 has 为助动词时

Collins.4

柯林斯词典

(尤当 has 为助动词时，what is 或 what has 的常用口语形式)
What'sis the usual spoken form of 'what is' or 'what has', especially when 'has' is an auxiliary verb.

What's wrong, my dearest? You look tired.
出什么事了，我最亲爱的？你看起来很疲惫。
'What's with this guy?' demanded an American voice in the row in front.
“这人怎么了？”前排有个美国人问道。
What's wrong?; What's happening?
出了什么事？
What's your speciality?
你的专长是什么？
Kids these days have no one to tell them what's right and wrong
如今的孩子没人告诉他们什么是对什么是错。
If you think I'm happy with what's left, you're very wrong.
如果你认为我对剩下的很满意，那你就大错特错了。
What's he drivelling about?
他胡说些什么？
What's the matter with you?--Just a bit of a headache; nothing serious.
你怎么了？--没啥，有点头疼。
What's the time?; What time is it?
几点钟了？
What's his attitude toward this business? Have you felt him out?
他对这事是什么态度？你摸底了吗？