Question: What opinion does the king of Brobdingnag form when Gulliver gives a description of England?
Answer: Unlike the Lilliputian Emperor, who primarily uses Gulliver as a weapon against Blefuscu, the Brobdingnagian King wants Gulliver to teach him English governance just in case there's something worth imitating there. Gulliver describes the English monarchy, Parliament, religion, and therefore the judiciary . Upon hearing these descriptions, the Brobdingnagian King answers that he cannot understand how the English avoid bribery, corruption, influence peddling, or hypocrisy, when there are not any safeguards against these sins in their government system. In fact, the King concludes, most Englishmen must be "the most pernicious race of little odious vermin that nature ever suffered to crawl upon the surface of the earth" (2.6.18). In other words, the English, according to the king of Brobdingnag, is nasty.
Again, the King of Brobdingnag is not a well-rounded character. We know nothing of his feelings, origins, any of that stuff which may make him seem more similar to a real person. That's not the point. His purpose is to direct the satire of the novel at England in an equal more pointed way than the Lilliput chapters did.