As soon as Harry tumbles out of the fireplace in the Burrow, Fred and George excitedly ask if Dudley ate the toffee. They explain that it's called Ton-Tongue Toffee as the kitchen explodes with laughter. The two oldest Weasley brothers introduce themselves. Charlie is stocky like the twins, while Bill, who works at Gringotts, is tall and looks undeniably cool. Suddenly, Mr. Weasley appears in the kitchen and shouts angrily at Fred. He yells that Dudley's tongue was four feet long before the Dursleys allowed him to shrink it and threatens to tell Mrs. Weasley. Mrs. Weasley appears and it becomes clear that Mr. Weasley never actually intended to tell his wife. As he shifts nervously, Hermione and Ginny appear and suggest that Ron and Harry come upstairs.
Bill and Charlie are some of Harry's first introductions to what life can be like after Hogwarts. Especially because Bill is described as being so cool, it makes it clear that Wizarding adulthood isn't all boring robes and teaching at Hogwarts--Bill later shares that his job is exciting and he's a treasure collector for Gringotts. Similarly, seeing Mr. and Mrs. Weasley's relationship offers a window onto what domestic Wizarding life looks like, especially in terms of parenting teenage sons figuring out how much they can get away with.
Harry follows Ron, Hermione, and Ginny as Ron explains that Fred and George have started a business called Weasley's Wizard Wheezes. He thinks their wares are brilliant, but Mrs. Weasley is furious that they didn't do especially well on their O.W.L. tests and don't want to get jobs at the Ministry. The group passes a door off the second landing and Percy pokes his head out to tell the group to be quiet. Percy tells Harry importantly that he's working on a report on thin cauldron bottoms before Ron sweeps them upstairs.
Again, Fred and George's desire to start a business shows that there are even more options for life after Hogwarts than what the three oldest Weasley brothers represent. Importantly, the fact that they performed poorly on their O.W.L.s indicates that the testing prepares students for a very particular career path, while it's clear that Fred and George aren't missing much given their goals.
In Ron's room, Harry notices the tiny owl. Ron explains that Ginny named the owl Pigwidgeon, which he hates, so he calls the owl Pig. He says that Percy loves work an unhealthy amount; he'll go on at length about his boss, Mr. Crouch, given the slightest opportunity. Ron begins to ask about Sirius but stops when he remembers that Ginny, who knows nothing about Sirius, is in the room. Hermione suggests they go downstairs to help with dinner.
Percy's love of his job and of his boss falls into line with what the reader knows of Percy from previous novels--he loves being important, working hard, and following rules, all things that will serve him well now that he works in the Ministry.
Mrs. Weasley is in a horrible mood as she magically peels potatoes and starts a soup. She angrily talks to herself about Fred and George's lack of ambition as Harry, Ron, and Hermione grab plates and silverware. They hurry out as Mrs. Weasley angrily picks up a wand that turns into a rubber mouse—one of Fred and George’s products. Outside, Bill and Charlie are levitating two long tables and making them smash into each other. Fred and George laugh while Percy yells out the window to stop. Several hours later, the tables are laden with food and Harry feels as though he's in paradise.
Mrs. Weasley's muttering again shows that she believes there are only a few "correct" paths for young people to take after finishing at Hogwarts, and that starting a joke shop isn't one of them. While Ron isn't yet thinking about the future much, this does begin to make it clear to him that he too should aspire to a Ministry job, even if it's not something he actually wants to do.
Percy talks on and on about Mr. Crouch and the preparations for the Quidditch World Cup. He says that Ludo Bagman, the head of the Department of Magical Games and Sports, isn't being helpful and isn't pursuing Bertha Jorkins's disappearance, even though she works for Bagman’s department. Percy and Mr. Weasley discuss how Bertha is hopeless and often gets lost, but Percy says that her disappearance is being overshadowed by the "top-secret" event that will happen after the World Cup. Ron rolls his eyes. Midway down the table, Mrs. Weasley tries to convince Bill to let her cut his hair and suggests he take his fang earring out, while further down, the twins and Charlie discuss the World Cup. With everyone else occupied, Ron asks Harry about Sirius. Finally, Mrs. Weasley sends everyone to bed.
Because the narration follows Harry and represents his inner thoughts, the reader is led to believe that they shouldn't necessarily take Percy seriously, given that Harry doesn't either. However, it's also telling that Percy says that Bagman isn't pursuing Bertha Jorkins's disappearance at all. Because the reader knows that Voldemort recently killed Jorkins, this suggests that the reader should pay attention to things that Percy says--and that Harry should think more carefully about Percy's words as well.