Idiom: To go the extra mile - to do more than what is required to reach a goal or complete a task; to do more and make a greater effort than what is expected.
Context #1 – Two friends talking during lunch
Lance: Hey, Brittany. You look really happy. What's up?
Brittany: Oh, I just finished my English Conversation class.
Lance: Really? I thought it ended at 12:30. It's 1:15 right now.
Brittany: Well, my teacher stayed after class and explained some idioms to me and how to use them in conversation. Now I really understand and I feel great.
Lance: What a nice teacher! It sounds like she really cares.
Brittany: Yes, she does. My teacher really goes the extra mile to help us understand new idioms in class. She often stays late and explains things to students with questions. She doesn't have to do that during her free time.
Lance: True! You are lucky to have a teacher like her.
Context #2 – Two friends talking about a party last Saturday
Sara: Did you like that party Billy threw for me last Saturday night for my birthday?
Pat: Yes! He really went the extra mile to make the perfect party for everyone.
Sara: I know! I totally didn't expect him to rent such a big room at the hotel and have the party catered with such delicious food! On top of that, he hired a live DJ to come in for the night. It was so nice!
Pat: Well, Billy is like that. He is a great guy and always willing to go the extra mile for his family and friends.
Meaning: To go the extra mile for someone means to do more than what is required to reach a goal or complete a task or to do more than what is expected of a person. In context 1, Brittany is happy because her teacher went the extra mile to help her understand something in English class. Therefore, the teacher did more than required to help Brittany understand the English lesson by staying during her own free time. In context 2, Billy threw a party for Sara and it was a super nice party. Billy did much more than what was expected to make it a great party.