These pronouns have to agree in gender and number with the nouns attached to them. For example:
mon fils = my son (masculine singular)
ma fille = my daughter (feminine singular)
mes enfants = my children (plural)
The words "my" (mon/ma/mes), "his/her" (son/sa/ses) and the informal "your" (ton/ta/tes) each have a masuline singular, feminine singular, and plural form. So we can change the above three examples as follows:
son fils = his/her son (masculine singular)
sa fille = his/her daughter (feminine singular)
ses enfants = his/her children (plural)
ton fils = your son (masculine singular)
ta fille = your daughter (feminine singular)
tes enfants = your children (plural)
"Our" (notre/nos), "their" (leur/leurs), and the formal and/or plural "you" (votre/vos), on the other hand, only have two forms: a gender-neutral singular and a plural. So with these pronouns, the same three examples would be as follows:
notre fils = our son (masculine singular)
notre fille = our daughter (feminine singular)
nos enfants = our children (plural)
leur fils = their son (masculine singular)
leur fille = their daughter (feminine singular)
leurs enfants = their children (plural)
votre fils = your son (masculine singular)
votre fille = your daughter (feminine singular)
vos enfants = your children (plural)
I hope this helps! I'd be happy to give more examples if you need them.