Metus puerum impedit, ne veritatem dicat.

The subject is metus.

Here metus is nominative singular, so it is the thing doing the action of impedit. In other words, fear is what prevents.

A learner may hesitate because metus is a fourth-declension noun, and its nominative singular ends in -us, which can look like a second-declension noun. But here it simply means fear and functions as the subject.

Puerum is the direct object of impedit.

The verb impedire means to hinder, to obstruct, or to prevent, and the person being hindered is put in the accusative. So:

• metus = fear
• puerum = the boy
• impedit = hinders / prevents

So literally: Fear hinders the boy.

Impedit is from impedire. Its basic sense is to entangle, to obstruct, to hinder, or to prevent.

In this sentence, it does not just mean that fear bothers the boy in a general way. It means that fear stops him from doing something specific, which is then explained by the ne clause:

• metus puerum impedit = fear prevents the boy
• ne veritatem dicat = from speaking the truth

So the whole construction is a common Latin way to say prevent someone from doing something.

After verbs of hindering, preventing, or stopping, Latin commonly uses ne + subjunctive.

So impedit, ne... means something like:

• prevents ... from ...
• literally, hinders ... lest ...

That can feel strange to an English speaker, because English usually says prevents him from speaking, not prevents him lest he speak. But in Latin this is normal.

So:

• metus puerum impedit, ne veritatem dicat
• literally: fear hinders the boy, lest he speak the truth
• idiomatically: fear prevents the boy from speaking the truth

Dicat is subjunctive, not indicative.

It is subjunctive because it is in a subordinate clause introduced by ne after a verb of preventing: impedit, ne...

This is a standard Latin construction. After verbs like impedire, prohibere, deterrere, and similar verbs of stopping or preventing, the verb in the ne clause is normally subjunctive.

So:

• dicit = he says / he is saying
• dicat = he may say / would say, or here simply the subjunctive required by the construction

The main verb impedit is present tense, so Latin normally uses the present subjunctive in a subordinate clause referring to action happening at the same time or after the main verb.

This is part of the sequence of tenses.

Here:

• impedit = present
• dicat = present subjunctive

The idea is that the preventing and the not-speaking are contemporaneous: fear is preventing the boy now from telling the truth.

If the main verb were past, you would usually expect an imperfect subjunctive instead, for example impediebat, ne ... diceret.

Veritatem is the direct object of dicat.

The verb dicere can take a direct object, and here the thing being said is the truth:

• veritatem dicat = he may say / speak the truth

So the accusative is not connected to impedit here; it belongs to dicat inside the subordinate clause.

The understood subject of dicat is the same person as puerum, that is, the boy.

Latin often leaves the subject unstated when it is clear from the context. Here the sense is:

• fear prevents the boy
• so that he does not speak the truth

So the understood subject of dicat is he, referring to the boy.

If Latin wanted to make that extra explicit, it could include a pronoun, but it usually does not need to.

Yes. Metus can be confusing because it belongs to the fourth declension, not the second.

Its nominative singular is metus, and its genitive singular is also metus. So the form by itself can look ambiguous to a beginner.

In this sentence, though, the syntax makes it clear that metus is nominative singular, because it is the subject of impedit.

Yes. The word order is perfectly natural Latin.

Latin word order is flexible, but this sentence is arranged quite clearly:

• metus at the beginning gives the cause or force doing the preventing
• puerum impedit gives the main statement
• ne veritatem dicat explains what the boy is prevented from doing

An English speaker may expect a more fixed order, but Latin often puts the important noun first and then places the ne clause after the main verb.

You could rearrange the words in other ways without changing the basic grammar, but this order is straightforward and readable.

That is a good idiomatic English translation, but it is not the most word-for-word translation.

A more literal version would be:

• Fear hinders the boy, lest he speak the truth

That sounds unnatural in English, so we usually translate it more idiomatically as:

• Fear prevents the boy from speaking the truth
• Fear keeps the boy from telling the truth

So the standard English translation captures the meaning well, even though the Latin structure is a bit different from normal English phrasing.