Whiteboard interviews are a style of interview question that assesses both the technical and non-technical skills of a potential hire. They can either be a specific algorithm and data structure problem, or they can be a more abstract systems design and architecture-based question.
What they are evaluating ?
Problem solving skills
Communication skills
Ability to articulate questions
Willingness to take in feedback
If you understand your limitations
Depth of technical understanding
The Advice: Communicate!
First, restart the question to make sure you understand the problem well