In unstressed positions (in the same manner as ⟨а⟩), ⟨ъ⟩ is normally pronounced /ɐ/, which sounds like Sanskrit "a" (अ), Portuguese "terra" [ˈtɛxɐ], or the German -er in the word "Kinder" [ˈkʰɪndɐ].

Before the reform of 1945, this sound was written with two letters, "ъ" and "ѫ" ("big yus", denoting a former nasal vowel).

In the Latin Belarusian alphabet (Łacinka), as in Polish, the hard sign's functions are performed by a following j rather than the i that would be present after a palatalized consonant.

Its function is to separate a number of prefixes ending in consonants from subsequent morphemes that begin with iotated vowels.

In native words, it is therefore only seen in front of the letters "я", "е", "ё", and "ю" (ja, je, jo, and ju in English).

It is sometimes used before "и" (i), non-iotated vowels or even consonants in Russian transcriptions of foreign names to mark an unexpected syllable break, much like an apostrophe in Latin script (e.g. Чанъань — Chang'an), the Arabic ʽayn (e.g. Даръа — Darʽa [ˈdarʕa]), or combined with a consonant to form a Khoisan click (e.g. Чъхоан — ǂHoan).

Because of the way this reform was implemented, the issue became politicized, leading to a number of printing houses in Petrograd refusing to follow the new rules.

To force the printing houses to comply, red sailors of the Baltic Fleet confiscated type carrying the "parasite letters".

According to the rough estimation presented in Lev Uspensky's popular linguistics book A Word On Words (Слово о словах / Slovo o slovakh), which expresses strong support for the reform, the final hard sign made up about 3.5% of printed text and thus wasted paper and ink, which provided the economic grounds for the reform.

Printing houses set up by Russian émigrés abroad kept using the pre-reform orthography for some time, but gradually they adopted the new spelling.

Meanwhile, in the USSR, Dahl’s Explanatory Dictionary was repeatedly (1935, 1955) reprinted in compliance with the old rules of spelling and the pre-reform alphabet.

For example, in Ossetian, the hard sign is part of the digraphs гъ /ʁ/, къ /kʼ/, пъ /pʼ/, тъ /tʼ/, хъ /q/, цъ /tsʼ/, чъ /tʃʼ/, as well as the trigraphs къу /kʷʼ/ and хъу /qʷ/.