The V is always pronounced as a W at the end of a word after a
vocal, after a vocal and before a consonant or at he beginning of a
word before a consonant. Examples: Stanislav (Stanislaw), Markov
(Markow), flavta (flawta), vklopiti (wklopiti, though most pronounce it
as uklopiti). Not necessary before R or L: vrata (vrata or wrata), vlak vlak or wlak).
Similar rules apply to Belarusian. For example, Vladislav is Uladzislaŭ in Belarusian where ŭ is pronounced similarly to ‘w’.
Belarusian language also has ‘akanye’. Unstressed letter ‘o’ is reduced to ‘a’. I read some Slovenian dialects also has this linguistic feature.