You describe her looks - hence the question is about what she "looks like." In other words, you describe her big eyes and long blonde hair. You can mention her age because age often affects how people look. Personality traits are not necessary to answer this question. I believe you're getting confused between these two questions: 1. "What does she look like?" 2. "What is she like?" #1 - describe her looks, hence "look like". #2 - describe her personality - notice there's no "look" before "like" in that question. And then there's of course also: 3. What does she like? - which means, obviously, what sort of things does she enjoy? The difference between #2 and #3 would be the verb involved, "is" and "does".

How does your sister look like? How to answer this question? Please

He/she means what does she look like visually? Hair, height, beauty, etc. It might be a question that should concern you haha