Rex potens exercitum ducit.

Because rex is in the nominative singular, the case normally used for the subject of a sentence in Latin.

The dictionary form is rex, regis = king. In this sentence, rex is the one doing the action of ducit, so it is the subject: the king.

Potens is an adjective meaning powerful. It describes rex.

So rex potens means the powerful king or a powerful king.

Because the adjective has to agree with the noun it describes in case, number, and gender.

• rex = nominative singular masculine
• potens = nominative singular, agreeing with rex

Even though the endings are not identical, they still match grammatically. Latin agreement is based on grammatical form, not on having the same ending.

In Latin, adjectives can come before or after the nouns they describe. Unlike English, Latin word order is much more flexible.

So:

• rex potens
• potens rex

can both mean the powerful king.

In this sentence, rex potens is a perfectly normal Latin order.

Because exercitum is in the accusative singular, the case normally used for the direct object.

The direct object is the person or thing receiving the action of the verb. Here, the king is leading the army, so exercitum is the object.

Because it is the accusative singular form of exercitus, meaning army.

This noun belongs to the fourth declension:

• nominative singular: exercitus
• accusative singular: exercitum

So the -um ending tells you that it is the direct object here.

Ducit is the third person singular present active indicative of ducere, meaning to lead.

So ducit means:

• he leads
• she leads
• it leads

In this sentence, since the subject is rex, it means the king leads.

It can mean either, depending on context.

Latin present tense often covers both:

• simple present: leads
• progressive present: is leading

So Rex potens exercitum ducit could be understood as:

• The powerful king leads the army
• The powerful king is leading the army

Latin does not have articles like English the or a/an.

So rex can mean:

• the king
• a king

and exercitum can mean:

• the army
• an army

You decide from context which English translation sounds best.

Yes. Latin word order is flexible because the endings show each word’s job in the sentence.

For example, these can still mean basically the same thing:

• Rex potens exercitum ducit
• Potens rex exercitum ducit
• Exercitum rex potens ducit

The basic meaning stays the same because:

• rex is still nominative
• exercitum is still accusative
• ducit is still the verb

Changing the order usually changes emphasis, not the core meaning.