Cucumis adhuc parvus est, sed mater dicit eum mox maturum futurum esse.

Because parvus has to agree with cucumis in gender, number, and case.

• cucumis = nominative singular masculine
• parvus = nominative singular masculine

So Cucumis adhuc parvus est means The cucumber is still small.

An English speaker may expect one unchanged adjective form, but in Latin adjectives change to match the noun they describe.

Here adhuc means still.

So:

• Cucumis adhuc parvus est = The cucumber is still small

Depending on context, adhuc can also mean up to this point, so far, or yet, but still is the most natural sense in this sentence.

Cucumis is nominative singular, because it is the subject of est.

It is also a masculine noun. That matters later in the sentence, because the pronoun eum and the adjectives maturum and futurum all match it in masculine singular form.

So even though English would say it for a cucumber, Latin treats cucumis as grammatically masculine.

Eum is the accusative singular masculine form of is, ea, id.

It refers back to cucumis. Since cucumis is grammatically masculine, Latin uses the masculine pronoun eum.

In English, we normally use it for objects, plants, and vegetables. Latin does not work that way here: the pronoun follows grammatical gender, not natural sex. So eum can be translated as it in this sentence.

Because Latin uses the accusative-and-infinitive construction after verbs of saying, thinking, knowing, and similar verbs.

Here the main verb is dicit = says. What the mother says is not introduced by that plus a normal finite verb, as in English. Instead, Latin says:

• mater dicit eum mox maturum futurum esse

Literally, this is something like:

• mother says him to be about to be ripe soon

A smoother English version is:

• mother says that it will soon be ripe

In this construction:

• the subject of the reported statement becomes accusative → eum
• the verb of the reported statement becomes an infinitive → futurum esse

Because Classical Latin usually does not use a separate word meaning that after verbs like say, think, know, hear, and so on.

Instead, it uses the accusative + infinitive construction:

• English: Mother says that it will soon be ripe
• Latin: Mater dicit eum mox maturum futurum esse

So the idea of that is built into the structure, rather than expressed by a separate conjunction.

Maturum is a predicate adjective meaning ripe, and it agrees with eum.

Since eum is:

• masculine
• singular
• accusative

the adjective must also be:

• masculine
• singular
• accusative

So:

• eum maturum = it ripe in the grammar of the indirect statement

In good English we would say that it will be ripe, but Latin shows the agreement very explicitly.

They are doing two different jobs.

• maturum = ripe
  This describes the state the cucumber will be in.
• futurum esse = will be / is going to be
  This expresses future time inside the indirect statement.

So:

• eum maturum futurum esse = that it will be ripe

A helpful way to think of it is:

• maturum tells you what it will be
• futurum esse tells you when / in what tense

Because after dicit, Latin changes the reported verb into an infinitive.

If we turn the indirect statement back into direct speech, it would be:

• Cucumis mox maturus erit.
• The cucumber will soon be ripe.

But after mater dicit, Latin does not keep erit. It changes the verb into the future infinitive:

• maturus erit → maturum futurum esse

So:

• direct statement: Cucumis mox maturus erit
• indirect statement: Mater dicit eum mox maturum futurum esse

Mox means soon.

It modifies the future idea:

• eum mox maturum futurum esse = that it will soon be ripe

Latin word order is more flexible than English word order, so mox can often move around without changing the basic meaning. Its position here is natural and clear.

The sentence has two main parts:

1. Cucumis adhuc parvus est
   = The cucumber is still small

2. sed mater dicit eum mox maturum futurum esse
   = but mother says that it will soon be ripe

So the pattern is:

• statement in the present: it is still small
• contrast with sed: but
• reported future statement after dicit: she says that it will soon be ripe

This is a very common Latin pattern, especially useful for learning indirect statement.