His/Her – son (m), sa (f) or ses (plural)
(Pronounced sohn, sa and say)
They wore his and her pyjamas but didn't have any for their son (son). He wasn't sad (sa) about it, you could say (ses) he was quite happy.
The french make no distinction between his and her, instead the word they use depends on the gender of the item, not the person. So to refer to a singular masculine item (e.g his/her chicken) is son, as chicken is masculine. A singular feminine item (e.g his/her beer) would be sa, as beer is feminine. But they use ses for plural items, whether they are masculine or feminine (e.g his/her books).