Puer in carru sedet, et mater dicit se ad villam aviae ire.

Because puer and mater are the subjects of their verbs, so they are in the nominative case:

• puer ... sedet = the boy sits
• mater dicit = the mother says

Latin marks subjects mainly by case endings, not by position in the sentence.

in carru means in/on the cart, using in + ablative to show location where something is.

• in
  • ablative = in / on / in the place of
• carru is ablative singular of carrus (cart)

So puer in carru sedet literally: the boy sits in the cart.

In Latin, in changes meaning depending on the case:

• in + ablative = in / on (location): in carru
• in + accusative = into / onto (motion toward): e.g. in carrum = into the cart

Here it’s in carru (ablative), so it’s location, not motion.

Latin word order is flexible. The ending tells you the grammar, so placement is often used for emphasis or rhythm.

• Puer in carru sedet is perfectly normal.
• Puer sedet in carru would also be correct. Often Latin places a prepositional phrase like in carru before the verb for a smooth flow.

This is indirect statement using the accusative + infinitive (often abbreviated ACI):

• dicit = she says
• se (accusative) = the subject within the indirect statement
• ire (infinitive) = the verb of the indirect statement

So mater dicit se ... ire = the mother says that she is going ...

Here se refers to mater (the mother), the subject of dicit. In indirect statement, se is typically a reflexive pronoun pointing back to the main clause subject:

• mater dicit se ... ire = the mother says that she herself is going

If the Latin meant “the mother says that the boy is going,” you’d expect eum (him) or puerum instead of se, depending on style.

Because after dicit in indirect statement, Latin uses an infinitive, not a finite verb:

• direct: eo ad villam = I am going to the house
• indirect: dicit se ad villam ire = she says that she is going to the house

So ire is the present infinitive of eo, ire (to go).

Both can involve motion, but they often differ in nuance:

• ad + accusative (ad villam) = to / toward (aiming at, approaching)
• in + accusative (in villam) = into (entering inside)

So ad villam can mean she’s going to the house (destination), without strongly emphasizing entering it.

aviae is genitive singular of avia (grandmother), showing possession:

• villa aviae = grandmother’s house / the grandmother’s estate
• In the sentence, villam is accusative because it’s the object of ad, so you get villam aviae = to grandmother’s house