A while ago, I found out about a linguistic concept called mutual intelligibility which describes the connection between different languages that share enough similarities that a non-speaker could understand the other language(s).
Wikipedia has an example of a Danish and Norwegian sentence:
English: I love eating Danish meat and drinking Norwegian water.
Danish: Jeg elsker at spise dansk kød og drikke norsk vand.
Norwegian: Jeg elsker å spise dansk kjøtt og drikke norsk vann.
Given their geographical and linguistic proximity, this one isn’t surprising. But I was surprised to see that Tunisian Arabic and Maltese shared 32–33% of sentences, according to a study from 2016.
Learning French and Spanish at school helped me figure words out in Portuguese thanks to the Romantic family connection (and the tons of Latin-based loan words in English!)
Language related: The Portuguese Language Orthographic Agreement of 1990, The Klingon language and its influence on modern culture, and 2 polyglots have an awesome chat in 21 languages