This question aims to reveal the circumstances around your departure from your current job. Primarily, they are looking for clues whether your employment was severed amicably or acrimoniously, whether you were fired, quit, laid off, or are still employed and exploring your options. Don't verbalize anything that could be misinterpreted and paint you in a negative light. Focus on the positives. Be specific about how this new position will help you take your career to the next level. Displaying professional gratitude for what you learned from your previous position can go a long way toward exhibiting emotional maturity.