Ruediger T. answered • 10/13/21
Language expert - German, English, French - 30 years experience
It is not exactly clear what your question is but I'm guessing that you are wondering about the cedilla (cédille) that appears in the nous form lançons.
Generally, in French, the pronunciation of the letter 'c' depends on the vowel that follows it. It is pronounced as in English cell or civil only when it is in front of 'e' or 'i'. In front of 'a', 'o', or 'u', it is pronounced as in cage, cold or cut. This creates an issue in certain verbs whose stem ends in 'c', as is the case in the example you've given here: lancer. In the infinitve form and all the conjugated forms we pronounce the 'c' as in English cell. But since the ending of the nous form - ons - begins with an 'o', the cedilla must be added to avoid pronouncing it as in English cold. In other words, the job of the cedilla is to keep the 'c' soft.
The same rules apply to the letter 'g'. It is pronounced soft as in gens (people) or gifle (slap) only when in front of 'e' or 'i', otherwise it is pronounced as in gomme (eraser). That way the same issue as discussed above arises with certain verbs whose stem ends in 'g'. Take manger: its nous form is not *mangons but mangeons, with an 'e' added in front of ons. The 'e' fulfills the same role as the cedilla in lançons: to keep the pronunciation of the 'g' soft.
