The Curious tale of Z and Cedilla.
Our modern cedilla symbol begun life as a "scribal ligature" which in plainer words means two characters combined into one by scribes as a kind of shorthand. The sounds cedilla represents in Roamnce language in one stage were written cz and had a Spanish nickname of cedilla or zedilla - the litte zeta. Originally the sound was probably "ts" and later became a "sh" sibilant sound partly due to the large number of Arabic and Hebrew speakers in Spain during the Islamic era.
It has been or is used in Spanish, Portugese, Catalan, Friuli and Occitan.
Beyond Europe it was adopted by several languages of the Turkkic family when they switched from Arabic and Cyrillic to Roman alphabets, Osmanli also known as Ottoman, Azeri, Tatar, Turkmen, and others.
While usuallu representing a sibilant one European Langaue Latvian uses it to mark Palatals to distinguish them from Velars and Nasals so it appears under g, K, L, and N.
Its use was much more common before IPA fonts were available.