What is the meaning of ů?

The thirty-fifth letter of the Czech alphabet, written in the Latin script; preceded by ú and followed by v, representing /uː/; homophonous with ⟨ú⟩.

The twenty-fifth letter of the Steuer Silesian alphabet, written in the Latin script; preceded by u and followed by w, representing /o/; equivalent to Ślabikŏrz ⟨Ō⟩.

Source: wiktionary.org