Cedilla
/sɪˈdɪlə/
Definition 1 of 1
Pro Tip 1/3Pronunciation Aid
A cedilla changes the 'c' sound from hard to soft when it comes before 'a', 'o', 'u'. 
In 'garçon', the cedilla gives the 'c' a soft sound.
Pro Tip 2/3Not English Origin
The cedilla is not originally used in English; it comes from languages like French and Portuguese. 
The word 'façade' in English borrows the cedilla from French.
Pro Tip 3/3Limited Use
The cedilla is rarely used in English and mainly appears in loanwords from other languages. 
We see a cedilla in 'soupçon', a French word used in English.