In a certain language, 'pit na som' means 'apples are sweet', 'na tor lig' means 'sweet mangoes ripen', and 'som tor mit' means 'are mangoes red'. Which word in that language means 'sweet'?

The first two sentences share exactly one code word, 'na', and exactly one English word, 'sweet', so na = sweet. Checking the rest: the first and third sentences share 'som' and 'are', so som = are; the second and third share 'tor' and 'mangoes', so tor = mangoes. Everything is consistent, and the word for 'sweet' is na.