Ligatures for “ль” and “нь” are unique to the Cyrillic alphabets of several Slavic languages in Southeastern Europe. We don’t have them in Bulgarian, so I can remember being confused the first time I saw them in Serbia. My confusion turned into fascination once I realized that their construction fused two characters that I knew how to use into one that we simply don’t have.
You can see љ (Lje) on this road sign for Жељуша in Serbia (with the Serbo-Croatian Latin representation below it):
Macedonian is a Slavic language closely related to Bulgarian. My untrained ear can’t tell the difference between the two, but my eyes spot differences immediately. In addition to minor variations in spelling and grammar, Macedonian’s Cyrillic alphabet uses a handful of characters not present in Bulgarian’s, for example the beautiful ligatures for “ль” and “нь”: љ and њ, respectively.