You may have already noticed that when -в occurs at the end of a word then it is commonly pronounced more like an F (ф). -вь is simply an extension of this rule.
The only difference is that when the вь occurs at the end of a word and follows a stressed vowel (for example, кровь), then there appears to be a tiny, tiny separation of -вь from the rest of the word.
When the vowel preceding the -вь is not stressed (for example, церковь) then there is no tiny separation of the -вь from the rest of the word.
Blood - [nonsense word]
кровь - кров
Pronounced:
krof - krov
Listen:
(Lena)
Listen:
(Lena)
Carrot - [nonsense word]
морковь - морков
Pronounced:
mar-kOf - mar-kov
Listen:
(Lena)
Listen:
(Lena)
Church - [nonsense word]
церковь - церков
Pronounced:
tsEr-kf - tser-kov
Listen:
(Lena)
Listen:
(Lena)
Stressed?
We probably don't need to remind you again ... when the Russian letter 'o' appears in a word, but is not stressed, then it is pronounced as a Russian 'a'.
If the 'o' is stressed (the syllable which is emphasised), then it is pronounced normally as a Russian 'o'.