。
What are your plans for tomorrow?
Literal
Tomorrow [possessive-の] plan [topic-は] how become-is [polite-です] [question-か].
どうなっていますか — literally 'how has-it-become?' — is a polite way to ask about a current state. The ~ている form turns 'become' into a state description: 'what state has it come to?' Used for asking about plans, progress, status of things.