What is the meaning of ů?

The 35th letter of the Czech alphabet, after ú and before v, and representing /uː/. Rhymes with do. The pronunciation is the same as ú – the use of ů or ú depends of their place in the word

The 25th letter of the Steuer Silesian alphabet, after U and before W, and representing /uː/. The pronunciation is the same as the Ślabikŏrz Ō.

Source: wiktionary.org