Puer in charta imaginem canis pingit.

Here is the grammatical breakdown:

• puer = the subject, in the nominative singular: boy
• in charta = a prepositional phrase: on paper
• imaginem = the direct object, in the accusative singular: image/picture
• canis = of a dog, modifying imaginem
• pingit = the verb: he paints / he draws

So Latin shows each word’s job mainly through its ending, not just through word order.

Because puer is in the nominative case, which is the case normally used for the subject of a sentence.

Also, pingit is third person singular, meaning he/she/it paints. Since puer is singular and is a person, it fits naturally as the subject: the boy paints.

Because imaginem is the accusative singular form of imago.

The verb pingit takes a direct object: the thing being painted. In this sentence, the boy is painting an image, so Latin uses the accusative:

• dictionary form: imago, imaginis
• accusative singular: imaginem

So imaginem means it is the thing directly affected by the action.

Here canis is functioning as a genitive singular, so it means of a dog.

It goes with imaginem:

• imaginem canis = an image of a dog

A tricky point is that for canis, the nominative singular and genitive singular look the same:

• nominative singular: canis = dog
• genitive singular: canis = of a dog

So you have to tell from context which one it is. After imaginem, the genitive reading makes sense.

Because the boy is not painting the dog itself. He is painting an image of the dog.

So the direct object is:

• imaginem = the picture/image

And canis just tells us what kind of image it is:

• imaginem canis = a picture of a dog

In English, this is the difference between:

• He paints a dog
  and
• He paints a picture of a dog

This sentence is the second kind.

Because in takes different cases depending on the meaning:

• in
  • ablative = location: in/on
• in
  • accusative = motion into/onto

Here the boy is painting on paper, so this is location, not movement. That is why Latin uses the ablative:

• in charta = on paper

If there were motion into something, Latin would use the accusative instead.

Because charta is a first-declension noun, and its ablative singular form is charta.

So although -a often makes learners think of nominative singular first-declension nouns, it can also be ablative singular, depending on the context.

Here the preposition in tells you that charta must be ablative.

Latin usually does not use articles like English the and a/an.

So puer can mean:

• the boy
• a boy

And imaginem can mean:

• the image
• an image

English has to choose whichever sounds best from the context. Latin leaves that unstated.

Latin often puts the verb near the end of the sentence, much more often than English does.

So puer in charta imaginem canis pingit is a very natural Latin word order.

Because Latin marks grammatical roles with endings, the word order is more flexible than in English. For example, these would still mean roughly the same thing:

• Puer imaginem canis in charta pingit
• Imaginem canis puer in charta pingit

But the emphasis may change slightly depending on what the speaker wants to highlight.

It can be understood as either, depending on context.

The basic idea of pingere is to paint, depict, or portray. In simple learning sentences, English may sometimes use draws if that sounds more natural with on paper.

So pingit here can reasonably be translated as:

• paints
• draws
• more broadly, depicts

The verb form pingit comes from the dictionary entry pingo, pingere, pinxi, pictum.

In this sentence:

• pingit = third person singular present active
• meaning: he/she/it paints

So with puer, it means the boy paints.

Because puer is one of the second-declension nouns that has -er in the nominative singular.

Not all second-declension masculine nouns end in -us. Some end in -er, for example:

• puer = boy
• ager = field

So puer is completely normal; it is just a different nominative pattern within the same declension.