Read the following passage and answer the questions.

My name's Lan. My best friend is Mi. She's 12 years old, like me! She has brown hair and brown eyes. Her favourite colour is blue. That's my favourite colour, too. She likes roller skating and cycling in summer. She has a dog called Tuti. I think that's a funny name! Mi is really nice. She is very funny. She makes me laugh a lot. She tells good jokes. Mi helps me in my lessons because sometimes I don't understand everything. We meet after school and do our homework together. We have a lot of fun. She's a good friend. She's always there for me. She understands my feelings and she cheers me up when I'm sad.

Why does Mi help Lan in the lessons?