we know his girl needs to be correct too... or would you not say that in French... how you can say that in English
Isn't it a bit of a double entendre, though? "His girl" might mean "his girlfriend"
"connaissons" is the conjugation for "nous" and it means "we are acquainted with".
"sais" is the conjugation for "je/tu" and it means "I/you know".
With people and places, "to know" translates to "connaître".
With things you have learned or before a verb in infinitive, "to know" or "to how to" translates to "savoir".
You can only know it by the context in a sentence, paragraph or conversation. It is something different about French that you have to get used to. Spanish works the same way, so i am used to it.
She is not his girl as in "his girlfriend", but his daughter.
Since in French the same noun is used for "girl" and "daughter", you have to show through your translation your understanding of "sa fille" as "his daughter".
For anyone who (like me) misheard "sa fille" as "ça fille", and is wondering why it was marked as incorrect, see Sitesurf's explanation of the difference in the words here: https://forum.duolingo.com/comment/147320/Cela-ce-ca-cette-c-est
The same: "nous connaissons sa fille". French possessive adjectives, like all other adjectives, agree in gender and number with the noun they modify. "Fille" is feminine singular, so "sa" is feminine singular as well.
- Sa fille = his/her/its daughter
- Son fils = his/her/its son
- Ses enfants = his/her/its children