Pastor vitulum ad arborem ligat.

Because pastor is in the nominative case, which is the case normally used for the subject in Latin.

Here:

• pastor = nominative singular = the shepherd
• It is the one doing the action of ligat

So the basic structure is:

• pastor = subject
• ligat = verb
• vitulum = direct object

The ending -um shows that vitulum is accusative singular.

The accusative case is commonly used for the direct object, the person or thing receiving the action of the verb.

So in this sentence:

• pastor ties
• vitulum is what he ties

Dictionary form:

• vitulus = calf
• vitulum = calf as direct object

This is a very common pattern in second-declension masculine nouns:

• nominative singular: -us
• accusative singular: -um

Because Latin uses the preposition ad to mean to, toward, or up to.

In ad arborem:

• ad = to, toward
• arborem = tree in the accusative singular

Together they mean something like to the tree or up to the tree.

If you removed ad, then arborem by itself would just be another accusative noun, and the sentence would no longer clearly express the idea of tying the calf to the tree.

Because the preposition ad takes the accusative.

That is a rule you should memorize:

• ad + accusative

So:

• dictionary form: arbor = tree
• after ad, it becomes arborem

This is not because arborem is the direct object of ligat. The direct object is vitulum.
Instead, arborem is accusative because it is the object of the preposition ad.

Ligat is a verb in the:

• present tense
• active voice
• indicative mood
• third person singular

It comes from ligare, meaning to tie.

The ending -t tells you the subject is:

• he
• she
• it

In this sentence, since the subject is pastor, ligat means the shepherd ties.

Because Latin often does not need a separate subject pronoun.

The verb ending already tells you the person and number:

• ligat = he/she/it ties

So Latin can simply say:

• Pastor vitulum ad arborem ligat

The noun pastor makes the subject even clearer, so adding a pronoun like is would usually be unnecessary.

Latin has no articles like English the or a/an.

So a noun like pastor can mean:

• the shepherd
• a shepherd

Likewise:

• vitulum can mean the calf or a calf
• arborem can mean the tree or a tree

You figure out which one sounds best from the context or from the translation provided.

Yes. Latin word order is more flexible than English word order because the noun endings show each word’s role.

So these could all mean essentially the same thing:

• Pastor vitulum ad arborem ligat
• Vitulum pastor ad arborem ligat
• Ad arborem pastor vitulum ligat
• Pastor ad arborem vitulum ligat

That said, word order can affect emphasis.

In many Latin sentences, the verb often comes at or near the end, so ligat in final position is very natural.

They are:

• pastor, pastoris = shepherd
• vitulus, vituli = calf
• arbor, arboris = tree
• ligo, ligare, ligavi, ligatum = tie, bind

A learner should get used to recognizing that the form in the sentence may differ from the dictionary form:

• pastor is already the dictionary form
• vitulum comes from vitulus
• arborem comes from arbor
• ligat comes from ligare

The nouns belong to different declensions:

• pastor, pastoris = third declension
• vitulus, vituli = second declension
• arbor, arboris = third declension

That is why their endings change differently.

For example:

vitulus

• nominative singular: vitulus
• accusative singular: vitulum

arbor

• nominative singular: arbor
• accusative singular: arborem

So even though both vitulum and arborem are accusative singular, they get there in different ways because they belong to different declensions.

A very common learner question. The key is to separate:

• the direct object
• the prepositional phrase

Here:

• vitulum is the direct object of ligat
• ad arborem is a prepositional phrase telling where the calf is being tied

So ask:

• What is the shepherd tying? → vitulum
• To what place or position? → ad arborem

The preposition ad signals that arborem belongs with it, so arborem is not a second direct object.

A simple Classical pronunciation would be approximately:

PAHS-tor WEE-too-loom ad AR-bo-rem LEE-gat

A few helpful points:

• v is pronounced like English w
• i is pronounced like ee
• g in ligat is always a hard g
• c and g do not soften before front vowels in Classical Latin

So:

• vitulum sounds like wee-too-loom
• ligat sounds like lee-gat

Yes. Ad often expresses direction or relation to something, and in a sentence like this it naturally gives the idea to the tree or against the tree.

Latin is not necessarily focusing on physical motion all the way from one place to another. It is expressing the idea that the calf is fastened to the tree.

So for an English speaker, the best way to understand it is:

• ad arborem = to the tree

That is simply the standard Latin way to express this relationship here.