In the Discworld books, most languages are basically the same as ones on Earth, with Morporkian being the equivalent of English. Others are parodies or combinations of real languages, like Latatian being bad Latin and Agatean having both Chinese and Japanese elements. Language plays a significant role in some of the books, notably the very first one, The Colour of Magic. When Twoflower, an Agatean tourist, arrives in the city of Ankh-Morpork, he speaks very little Morporkian. He has a phrase book, but it isn’t particularly useful. It’s pointed out that he thinks everyone should understand him if he speaks his own language loudly and clearly. Even though I know this is ridiculous, I’ve fallen into that trap myself when talking with someone who doesn’t speak English. It’s unfortunately kind of natural, I guess. Anyway, Twoflower meets up with the failed wizard Rincewind, who while bad at pretty much everything else except running away does have a gift for languages. The two of them are able to converse in Trob, a language spoken on a group of islands in between Ankh-Morpork and the Agatean Empire. After they leave the city, however, the language is no longer an issue, and Twoflower is apparently able to talk to other residents of the area without needing Rincewind to translate. The Sky One movie gets around this and the need to have constant translations by revealing that Twoflower took a correspondence course in Morporkian. As it stands in the book, it’s somewhat of a plot hole. When Rincewind visits the Agatean Empire in Interesting Times, he’s able to read and speak Agatean, but there’s a running gag about how he keeps screwing up the inflection.
Language makes for a few plot holes in other books as well. In Small Gods, the illiterate Omnian Brutha has no problem talking to the people in Ephebe, basically the Discworld version of Greece.
Picture by Thaumivore
Then again, he DOES have a perfect memory, and might have learned spoken Ephebian. More problematic is another Rincewind book, Eric. The story makes a point of how Rincewind can only read the Tezuman language and not speak it, and Eric can’t understand it at all. Later, however, they end up in ancient Tsort and talk to the Ephebian soldiers with no difficulty.
Mind you, Rincewind IS being manipulated by the demon Vassenego, who might have just provided translations when it suited him.