Cum uvae maturae erunt, puellae ad colligendas uvas in vineam venient.

No. Here cum means when.

Latin cum can have more than one meaning:

• cum
  • ablative noun/pronoun = with
• cum as a conjunction introducing a clause = when, since, or although, depending on context

In this sentence, cum uvae maturae erunt is a clause, so cum is a conjunction meaning when:

• Cum uvae maturae erunt = When the grapes are ripe / When the grapes have become ripe

Erunt is future tense, from sum, esse (to be). It means they will be.

So:

• uvae maturae erunt = the grapes will be ripe

Latin uses the future here because the whole situation is set in the future:

• first, the grapes will be ripe
• then, the girls will come

That is why both verbs are future.

Because the main action is also in the future.

• venient = they will come

The sentence is describing something that will happen later:

• When the grapes will be ripe, the girls will come into the vineyard to gather grapes

In smoother English we often say When the grapes are ripe, the girls will come..., but Latin can use the future in both clauses here.

Because maturae is an adjective agreeing with uvae.

• uvae = grapes
• maturae = ripe

Both are:

• feminine
• plural
• nominative

So they match, as Latin adjectives normally do.

This phrase is literally:

• uvae maturae = ripe grapes

Since uvae is the subject of erunt, it has to be nominative, and the adjective matches it.

Puellae is nominative plural here, and it is the subject of venient.

So:

• puellae ... venient = the girls will come

A learner may notice that puellae can have more than one meaning in Latin morphology, but here the verb makes the function clear:

• venient is plural
• so puellae is naturally understood as the girls (nominative plural), not dative singular or something else

They are the same noun in different cases because they play different roles.

• uvae = nominative plural, the subject of erunt
• uvas = accusative plural, the object of colligendas

So:

• Cum uvae maturae erunt = When the grapes are ripe
• ad colligendas uvas = to gather the grapes / for gathering grapes

English often uses the same form grapes in both places, but Latin changes the ending to show the grammatical job.

It expresses purpose: to gather grapes or for gathering grapes.

• ad
  • accusative can mean for or for the purpose of
• here it tells us why the girls are coming

So:

• puellae ... venient = the girls will come
• ad colligendas uvas = to gather grapes

Together:

• the girls will come to gather grapes

This is a very common learner question. Latin often expresses purpose with:

• ad
  • gerundive + noun

rather than:

• ad
  • gerund + object

Here colligendas is a gerundive, agreeing with uvas:

• colligendas = feminine accusative plural
• uvas = feminine accusative plural

So literally it is something like:

• for grapes-to-be-gathered

But in natural English, just translate it as:

• to gather grapes
• for gathering grapes

This construction is very common in Latin when the verbal idea has a direct object.

Colligendas is the gerundive of colligo, colligere, meaning gather or collect.

In this sentence it agrees with uvas:

• uvas = feminine accusative plural
• colligendas = feminine accusative plural

So the phrase ad colligendas uvas is a standard Latin way to say:

• to gather grapes
• for gathering grapes

Even though the gerundive can sometimes have a passive flavor in other contexts, here the whole phrase is best understood simply as a purpose expression.

Because in takes different cases depending on whether it shows motion toward or location.

• in
  • accusative = into, to, motion toward
• in
  • ablative = in, on, location

Here the girls are coming into the vineyard, so Latin uses the accusative:

• in vineam = into the vineyard

If the sentence were talking about being in the vineyard without movement, you would expect:

• in vinea = in the vineyard

Vineam is accusative singular.

It is accusative because it follows in in the sense of motion toward:

• in vineam venient = they will come into the vineyard

The noun is vinea, vineae (vineyard), first declension.

Because Latin word order is much more flexible than English word order.

Putting the verb at or near the end is very common in Latin, especially in straightforward prose and teaching sentences. So:

• Cum uvae maturae erunt, puellae ad colligendas uvas in vineam venient.

is perfectly normal.

Latin uses endings, not word order alone, to show grammatical relationships. That means the sentence can often be rearranged without changing the core meaning, though the emphasis may shift.

No. Here cum is introducing a simple temporal clause referring to a future event, so the indicative is used:

• erunt = future indicative

Learners often meet cum with the subjunctive in other kinds of clauses, especially when cum means since or although, or in certain narrative contexts. But that is not what is happening here.

Here it is simply:

• when the grapes are ripe / when the grapes will be ripe

So the indicative is expected.

Only up to a point. A very literal breakdown would be:

• Cum = when
• uvae = the grapes
• maturae = ripe
• erunt = will be
• puellae = the girls
• ad = for, to
• colligendas uvas = gathering grapes / grapes to be gathered
• in vineam = into the vineyard
• venient = will come

But good English usually smooths this out:

• When the grapes are ripe, the girls will come into the vineyard to gather grapes.

So a completely word-for-word translation is useful for grammar study, but not always for natural English.

A helpful breakdown is:

Subordinate clause

• Cum uvae maturae erunt
• When the grapes are ripe

Main clause

• puellae ... venient
• the girls will come

Purpose phrase

• ad colligendas uvas
• to gather grapes

Prepositional phrase showing direction

• in vineam
• into the vineyard

Seeing those chunks makes the sentence much easier to read.