These are not B's. In the Russian language But is pronounced as the English equivalent V, Б is pronounced as English B, Ь is a soft sound indicator, Ы is pronounced as I as in big, bill, fill etc.
Today, both the Hard sign (Ъ) and the Soft sign (Ь) are used to separate a consonant and a vowel (mostly Я, Ё, Е, Ю), only the Hard sign (Ъ) separates a Hard consonant and a vowel, and the Soft sign (Ь) separates a Soft consonant and a vowel. In some other languages, a similar function is given to an apostrophe.
The letter "ь" does not have any sound itself. It softens the letter before it. For example the words "есть" (to eat) and "ест" (he/she eats) sound different thanks to "ь".
The soft sign (Ь, ь) is a letter in the Cyrillic script that is used in various Slavic languages. In Old Church Slavonic, it represented a short or reduced front vowel. However, over time, the specific vowel sound it denoted was largely eliminated and merged with other vowel sounds.
Letters: Ь
This letter is called “soft sign” (м'який знак in Ukrainian). As the name of the letter suggests, its purpose is to soften the sound of the previous letter. Usually, the difference between the softened and not-softened sound is very difficult to notice for a foreign ear.
Russian ⟨ы⟩ is used to transliterate Polish ⟨y⟩ into Cyrillic: Maryla (Марыля). However, Latin ⟨y⟩ may be used for other purposes as well (such as for ⟨й⟩, or as part of digraphs, e.g. ⟨я⟩). In most Turkic languages that use Cyrillic, ⟨ы⟩ represents the close back unrounded vowel /ɯ/, like in Kazakh, Kyrgyz, etc.
Letter. ы (upper case Ы) A letter of the Cyrillic script, called y or yeru.
The Letter Ы
This vowel sound should be pronounced like something between “i” and “u.” For the right pronunciation, try to say “u” with your lips open as if you're saying “i.”
In unstressed positions (in the same manner as ⟨а⟩), ⟨ъ⟩ is normally pronounced /ɐ/, which sounds like Sanskrit "a" (अ), Portuguese "terra" [ˈtɛʁɐ], or the German -er in the word "Kinder" [ˈkʰɪndɐ].
ь and ъ are used to make a letter such as 'л' softer, or separate two colliding letters. The two serve the same purpose and will be often mixed up. Ы is not used to separate anything or mak something softer. In fact, you will hear it makes the sound harder.
ъ in Russian
Russian alphabet has the hard sign (ъ), but Ukrainian doesn't (in Ukrainian, the apostrophe is used instead (').
-Й- normally signifies /j/ (voiced palatal approximant). -И- signifies /i/ (close front unrounded vowel), but in unstressed syllables it can be reduced to /ɪ/ (near-close near-front unrounded vowel). -Ы- signifies /ɨ/ (close central unrounded vowel). The linked articles have audio samples.
Short I or Yot/Jot (Й й; italics: Й й) (sometimes called i-kratkoye, Russian: и-краткое) is a letter of the Cyrillic script. It is made of the Cyrillic letter И with a breve. Cyrillic letter Short I.
The sound of the letter "ы" is one of the few difficult sounds in the Russian language. In this course we represent its sound like this: [y]. The sound of "ы" has no English equivalent but it resembles the sound [i:] as in "be", "mean" or "three".
а о у э ы - indicate that the preceding consonant is hard. я ё ю е и and ь - indicate that the preceding consonant is soft.
Russian's ы lies somewhere between the [i] sound in the English word "hockey" and the [u] sound from "boom". If you watch your lip position and practice going back and forth between these two sounds you should be able to find the ы sound.
The problem, in Moscow's view, was that the Ukrainian g has no Russian counterpart. The letter that Russians call g carries the h sound in Ukrainian. By order of the people's commissars in charge of spelling in 1933, that letter became both g and h for Ukrainians.
The most popular phrase is “pryvit” – which is the equivalent of “hi” or “hello” in Ukrainian.