"What is it?"
With proper accents, "Qué está" translates "What is it?", but we have to remember the difference between ser (es) and estar (está); if you're going to describe what something is--its characteristics--you're using ser, not estar.
Ser and Estar can be very specific at times, but the jist can be "ser is for permanent conditions and estar is for temporary conditions". For more details, please see studyspanish.com's write-up. This will be very helpful and I highly suggest you pay a visit.
I imagined someone saying “What is it?” to someone who was crying, or looking sad. In this case “¿Qué pasa?” should be a valid translation, right?