remysapienza: Rewording to make the grammar more obvious:
Habētis • ( You ) • Subject Plural
Habētis • Do have • Verb Transitivé
Quot • How many • Direct Object Determiner Adjective Indeclinable
Fīliās • Daughters • Direct Object Noun, Plural, Accusative Case
[ Have ] Verb + [ Daughters ] Direct Object, Plural, in Accusative Case - the recipient of the action of being had [ Have ].
[ Quot ] is a quantifying Determiner, a Latin single word, for which English does not have single, word for word, equivalent. Treat [ Quot ] as an Adjective Determiner of [ Daughters ]. [ Quot ] does not decline so it displays no Inflection variation, as does its Noun, [ Fīlias ], which is a Feminine Plural word in the Accusative Case:
The English word How, is frequently an adverb but, in this expression it does not address the attributes of the Verb: [ Have ], rather it is part of the two word, [ How many ], quantifying Determiner. Other similar Determiner x examples:
You have / do not have: x daughter/s.
Do you have / Have you x daughters?
x = a, any, many, no, two, so many, too many, quite so many, way too many, way too few, some, nary a, quite a few, [ Zero Null • You have daughters. Zero Null Article Determiner, & etc.
Quot Determiner - Indeclinable
Habēre + Direct Object in Accusative Case
I had a similar question and someone said the easiest way to think of this is kind of like the difference between "they" and "them".
Rough example tied back to this exercise: - Correct: "How many of 'them' (filias) do you have?" - Incorrect: "How many of 'they' (filiae) do you have?"