When he hears the mail arrive, Ove says "I won" to the cat. The narrator explains that Ove and Rune used to bet on when the mail would arrive and had a complex system since the mail arrived at noon. Now, the mail comes at any point during the day. Ove tried to make bets with Sonja after he stopped talking to Rune, but soon gave up.
The complex system to time the mail reflects Ove and Rune's shared love of rules and specifics. Notice that Ove was very happy when he got to share that love with someone; it's not nearly as much fun when he's alone or with someone who doesn't get it.
Ove throws the door open and nearly hits the youth, who is wearing a postman's uniform and standing outside. Ove asks the youth what he wants and notices that it's the same youth who was trying to fix the lady's bike the other day. The youth hands Ove his mail and explains that he's bringing him the mail, since the mailbox is smashed. Ove examines his mail. He has one letter that is hand-addressed, but Ove knows that's just an advertising trick. The youth doesn't leave and finally asks Ove if his wife's name is Sonja. He continues, saying that he noticed Ove's last name and had a teacher with the same name. The youth starts a question, but then turns to leave. Ove asks the youth to finish, and the youth said he liked Sonja a lot and she's the only teacher who didn't think he was dumb.
Whatever Ove thinks about "kids these days," this teenager has a job (and, notably, a job in which he actually does something) and is kind enough to bring the mail to the door. When the youth speaks about Sonja, the reader is given concrete evidence that Sonja was successful in giving back to her community and doing good things for the world. Ove's suspicion about the hand-addressed letter shows that he's not fully come around to trusting people yet, though his willingness to talk to the youth indicates that he's certainly getting better.
Ove and the youth stand for a minute and remember Sonja, and finally Ove asks the youth what he was doing with the bike. The youth repeats his story again that he's fixing the bike for his girlfriend, but adds that she's not his girlfriend yet. Ove asks if he has any tools. The youth doesn't, and Ove asks why he promised to fix the bike. The youth responds that he loves the girl, and then turns to leave. Ove tells him to come over after work to pick up the bike.
Ove is coming around. He doesn't berate the youth for talking and being unable to do anything he's talking about, and further, he offers to help the youth perform the task. The youth here shares similar qualities to young Ove on the construction site, suggesting that some memories repeat in later generations.
The youth looks suddenly excited, but asks to come tomorrow since he has another job. Ove asks what the other job is, and the youth says he works in a cafe. He explains that he's saving money to buy a car and says he's looking at a Renault. Ove loses his composure and yells that the youth can't buy a French car, and then asks how the youth plans on getting the bike to the cafe without a car. Ove shakes his head and asks which cafe he works at.
It's one thing for the youth to be lovestruck and unable to perform tasks, but wholly another for him to want to buy a foreign car. Now the youth is truly becoming a project for Ove, as it's obvious that Ove will attempt to steer him towards an appropriate car brand. In doing so, Ove learns that he can feel superior and become a part of the community.
Twenty minutes later, Ove knocks on Parvaneh's door and asks her if she has the signs to put on the car to indicate she's a student driver. She says yes, and he tells her that he'll be back to pick her up for her first lesson in two hours.
Parvaneh's bet that Ove wouldn't let anyone else teach her to drive proves correct. Ove will share his principles now with Parvaneh and the youth, while making sure neither of them are "ruined" by someone less principled.