Avus baculum tenet, quia sine baculo per vicum ambulare non audet.

Because they are in different cases.

• baculum is accusative singular, used as the direct object of tenet: Avus baculum tenet = Grandfather holds a stick.
• baculo is ablative singular, because the preposition sine takes the ablative: sine baculo = without a stick.

This is a very common thing in Latin: the same noun changes its ending depending on its job in the sentence.

Avus is nominative singular.

It is the subject of tenet and audet—the person doing the actions:

• Avus ... tenet = Grandfather holds ...
• ... non audet = ... he does not dare

In Latin, the subject is normally in the nominative case.

In Latin, many prepositions require a particular case. Sine always takes the ablative.

So:

• sine baculo = without a stick
• not sine baculum

This is something you usually just memorize with the preposition:

• cum
  • ablative
• sine
  • ablative
• ex
  • ablative and so on.

Because per means through and takes the accusative.

So:

• per vicum = through the street
• in vico would mean in the street or on the street, depending on context

Latin often distinguishes these ideas more clearly than English:

• per
  • accusative = movement through
• in
  • ablative = location in/on
• in
  • accusative = motion into

So per vicum ambulare means specifically to walk through the street.

Because it depends on audet.

The verb audeo, audere means to dare, and it is commonly followed by an infinitive:

• ambulare non audet = he does not dare to walk

This works much like English:

• He dares to walk
• He does not dare to walk

So ambulare is the action that he does not dare to do.

Because non negates the verb audet.

• audet = he dares
• non audet = he does not dare

In Latin, non usually goes directly before the word or phrase it negates, and very often that is the verb.

Quia means because.

It introduces a clause giving the reason:

• Avus baculum tenet = Grandfather holds a stick
• quia ... non audet = because ... he does not dare

So the second clause explains the first one.

Latin word order is more flexible because the endings show each word’s role.

In this sentence:

• Avus is the subject
• baculum is the direct object
• baculo is ablative after sine
• vicum is accusative after per

Because the endings already tell you what each word is doing, Latin does not rely on word order as much as English does.

A more English-like order would be something like:

• Avus baculum tenet, quia non audet sine baculo per vicum ambulare.

That would still be Latin. The actual order places sine baculo before per vicum ambulare, which helps emphasize the important condition: without a stick.

Yes.

• tenet = he holds / is holding
• audet = he dares

Both are 3rd person singular present tense, matching avus.

Depending on context, English may translate the Latin present in different ways:

• holds
• is holding
• does dare / dares

Here the most natural translation is usually:

• Grandfather is holding a stick, because he does not dare to walk through the street without a stick.

Because Latin usually expresses to walk simply with the infinitive ambulare.

English often uses to + verb for the infinitive:

• to walk

Latin uses a special verb form instead:

• ambulare

So:

• audet ambulare = he dares to walk

The to is built into the way English translates the infinitive, but Latin does not need a separate word for it.

Yes, very possibly.

Baculum basically means stick, staff, or cane, and in a sentence like this it is very natural to understand it as a walking stick or cane.

Because the sentence says he does not dare walk through the street without it, the context strongly suggests it is something he uses for support, not just a random piece of wood.

Because vicum is not the object of ambulare by itself here; it belongs with the preposition per.

• ambulare = to walk
• per vicum = through the street

So the structure is:

• [per vicum] [ambulare]
• to walk [through the street]

Latin often uses prepositional phrases to show where movement happens.

Mostly yes, but learners often notice something a little unusual about audeo.

Its dictionary form is:

• audeo, audere, ausus sum

It is one of the so-called semi-deponent verbs:

• in the present system, it looks active: audeo, audes, audet
• in the perfect system, it uses forms that look passive but have active meaning: ausus sum = I dared

For this sentence, though, you only need the present form:

• audet = he dares

So nothing strange is happening here yet, but this verb does have an unusual full paradigm.