I fully agree on what Antonello has shared.
Focusing on what you have done to improve yourself through the lessons earned from the failure experience and how it tranformed you going forward is a key insight that needs to be expanded in answering this type of question.
This particular question typically aimed to assess at least 3 key things from the prospective candidates:
- Willingness to accept that one has made a mistake (humility & integrity)
- Capability to learn
- Tenacity & persistency
Presenting the response in the following structure will help you in setting up a distinctive answer:
- Failure experience and lessons derived from it
- Efforts done to improve yourself based on the learnings obtained
- Example of post-failure events where you succesfully overcame similar pitfalls by applying improved methods and utilizing your improved skillsets
More specifically, for the third element, if the learnings influences crucial decisions following the failure experience such as your career path, it will be an exceptional showcase of how one is willing to accept and learn from their mistake and turning it into strengths for their future endeavors.
Always remember that people grow through mistakes. The most important thing is to raise yourself up and becoming better by learning from it.
Hope it helps.