The Sheikah Language is a language used by the elusive Sheikah tribe in the Zelda series. Even if the Sheikah have existed since The Legend of Zelda: Ocarina of Time, the language was not invented until The Legend of Zelda: Breath of the Wild as it marks the first time more than a few Sheikah is shown in a game. They play an important role in the backstory of the entire series but in Breath of the Wild they were once the most advanced civilization in Hyrule with technological wonders found everywhere. The Sheikah Script is found mostly on those ancient machines. The language itself has been shown to have existed for at least 10,000 years by the time of Breath of the Wild. The primary language of the Kingdom of Hyrule is still the Hylian Language, however, and most Sheikah are able to communicate in the Sixth Hylian Script used at the time.
The transcript itself is a cipher of both the Latin alphabet used in the english language and of the arabic numbers that are used with almost all Latin based languages. Despite that, the Sheikah language has still a few quirks that differenciate it from other Hyrulean languages. It is the only known Hyrulean language to use arabic numbers aside from the Third Hylian Script. It is written without space, meaning that punctuation is the only way to know where a phrase end and every words have no space between them.
Every character is made to fit within an invisible, uniform square and are thus completely angular in shape. Hylians are mostly unable to read Sheikah as Link cannot comprehend corrupted portions of the Sheikah Slate that appear in the Sheikah language.