Short answers, pulled from the story.
The acute accent is a diacritic mark used in alphabets based on the Latin, Cyrillic, and Greek scripts. Depending on the language, it marks stress, pitch, vowel height, vowel length, tone, or serves to distinguish between homophones.
Geoffroy Tory, the royal printer of France, first used the acute accent in French in 1530.
In the polytonic orthography of Ancient Greek, the acute accent indicated a syllable with a high pitch. The Greek name for the accented syllable was oxeîa, meaning sharp or high, which was translated into Latin as sharpened.
In Pinyin, the acute accent marks the second tone, which is a rising tone going from low to high. As an alternative, the number 2 can be written after the syllable: lái is equivalent to lai2.
The Polish kreska looks similar to the acute accent but is considered a distinct diacritic. It is more nearly vertical and positioned slightly right of center, and on consonants it signals palatalization rather than stress or vowel quality. Unicode assigns both marks to the same code points, which creates challenges for type designers.
In Icelandic and Faroese, letters such as á, é, í, ó, ú, and ý are treated as fully independent letters of the alphabet, each with its own distinct pronunciation, not merely modified versions of the base vowel. They trace etymologically to Old Norse long vowels that shifted into diphthongs over time.