Haec quaestio ad valetudinem pueri pertinet.

Quaestio is nominative singular. It is the subject of the verb pertinet, so it has to be in the nominative. The basic backbone of the sentence is:

Haec quaestio ... pertinet
= This question ... pertains

Because it follows the preposition ad, and ad takes the accusative case. So:

• ad = to, toward, with reference to
• valetudinem = accusative singular of valetudo

In this sentence, ad valetudinem means something like with reference to the health or concerning the health.

Because pertinere ad is a normal Latin expression meaning to pertain to, to relate to, or to have to do with. English uses to after pertain, but Latin commonly uses ad + accusative.

So you should learn pertinet ad as a phrase or pattern, not just the verb by itself.

Pueri is genitive singular, meaning of the boy. It depends on valetudinem, so valetudinem pueri means the boy’s health.

This is a very common Latin use of the genitive: one noun modifies another to show possession or close relationship.

Yes, pueri can be either:

• nominative plural = boys
• genitive singular = of the boy

But here it must be genitive singular, because it fits naturally with valetudinem: the health of the boy. A nominative plural boys would not fit the sentence structure.

Pertinet is 3rd person singular, present active indicative of pertinere.

So it means he/she/it pertains or it relates. Since the subject is haec quaestio, the sense is:

this question pertains / relates

Latin word order is more flexible than English word order because the endings show the grammar. Putting the verb at the end is very common in Latin, especially in straightforward prose.

So:

Haec quaestio ad valetudinem pueri pertinet.

is a very natural Latin order:

• subject first: haec quaestio
• then the related phrase: ad valetudinem pueri
• then the verb: pertinet

English usually prefers the verb earlier, but Latin often saves it for the end.

It breaks down like this:

• Haec = demonstrative adjective, nominative feminine singular, modifying quaestio
• quaestio = noun, nominative singular, the subject
• ad = preposition taking the accusative
• valetudinem = accusative singular, object of ad
• pueri = genitive singular, modifying valetudinem
• pertinet = main verb, 3rd singular present

So the structure is:

Subject + prepositional phrase + verb

That is:

Haec quaestio + ad valetudinem pueri + pertinet

No. Grammatical gender in Latin is not the same as biological sex. Quaestio is grammatically feminine because that is the gender of the noun, not because a question is female in any real-world sense.

So haec is feminine only because it must agree grammatically with quaestio.