Lje represents a palatal lateral /ʎ/, a sound similar (but not identical) to the palatalized alveolar lateral approximant /lʲ/, which is in some languages represented by the digraph ⟨ль⟩ and pronounced /lʲ/ like the ⟨ll⟩ in "million".

Compare Latvian ⟨ļ⟩, Slovak ⟨ľ⟩, Portuguese ⟨lh⟩, Spanish ⟨ll⟩ and Italian ⟨gl⟩.

[1] It was invented by Vuk Stefanović Karadžić for use in his 1818 dictionary, replacing the earlier digraph ⟨ль⟩.

[1] It corresponds to the digraph ⟨Lj⟩ in Gaj's Latin alphabet for Serbo-Croatian.

[1] It is today used in Macedonian, variants of Serbo-Croatian when written in Cyrillic (Bosnian, Montenegrin and Serbian), and Itelmen.