Mereka menandatangani perjanjian itu.

Mereka is the usual Indonesian third-person plural pronoun: they / them.

In this sentence, it is the subject, so it comes before the verb:

• Mereka = the people doing the action

A few useful notes:

• It does not show gender, so it can mean they for any group of people.
• It is normally used for people, not usually for things.
• Indonesian does not change pronouns for subject/object the way English does, so mereka can mean either they or them depending on position in the sentence.

The verb menandatangani is built from tanda tangan, which literally means signature and is also associated with the idea of signing.

In standard Indonesian, menandatangani means to sign something.

It is formed with:

• meN- = an active verb prefix
• base related to tanda tangan
• -i = a suffix that helps form a transitive verb

So this is a very typical Indonesian pattern: a base word gets affixes added to create a more specific grammatical form.

Also, in standard spelling, the derived verb is written as one word:

• menandatangani

This is because of how the meN- prefix behaves.

When meN- attaches to a base beginning with t, the t usually disappears. This is a common sound/spelling change in Indonesian.

For example:

• tulis → menulis
• tanya → menanya (though bertanya is more common in real use)
• tanda tangan → menandatangani

So menandatangani follows a regular pattern.

In many Indonesian verbs, -i helps create a verb that takes an object and often gives the sense of acting on, toward, or with respect to something.

Here, menandatangani means to sign something, and the thing being signed is the direct object:

• menandatangani perjanjian itu

So the verb naturally connects to the object perjanjian itu.

You do not need to translate -i separately every time, but it is useful to know that it helps shape the verb into the standard transitive form.

Janji means promise.

Perjanjian is a noun formed from janji and usually means:

• agreement
• contract
• treaty
• arrangement

So:

• janji = a promise
• perjanjian = an agreement or formal promise between sides

In this sentence, perjanjian is more formal and fits the idea of a document or agreement that can be signed.

In Indonesian, demonstratives like ini and itu usually come after the noun.

So:

• perjanjian itu = that agreement or the agreement
• rumah itu = that house / the house
• orang ini = this person

This is normal Indonesian word order for noun phrases.

Also, depending on context, itu can sometimes sound like English that, but it can also function a bit like the when referring to something already known in the conversation.

Indonesian verbs do not change form for tense the way English verbs do.

So menandatangani does not by itself mean:

• signed
• are signing
• will sign

The time is usually understood from:

• context
• time words
• aspect markers

For example:

• Mereka sudah menandatangani perjanjian itu. = They have already signed the agreement.
• Mereka sedang menandatangani perjanjian itu. = They are signing the agreement.
• Mereka akan menandatangani perjanjian itu. = They will sign the agreement.

Without extra markers, the sentence is neutral and depends on context.

Yes. This sentence uses the basic Indonesian order:

Subject + Verb + Object

• Mereka = subject
• menandatangani = verb
• perjanjian itu = object

So it is a very standard sentence pattern.

Indonesian can also express the same idea in other ways, especially with passive structures, for example:

• Perjanjian itu ditandatangani oleh mereka.
• Perjanjian itu mereka tandatangani.

But the original sentence is the straightforward active pattern.

Yes, in everyday spoken Indonesian, many people would say:

• Mereka tanda tangan perjanjian itu.

That sounds more conversational and less formal.

By contrast:

• Mereka menandatangani perjanjian itu.

sounds more standard, careful, and formal.

So both can be understood, but menandatangani is the better choice in formal writing, news, official language, and textbooks.

Yes.

Although itu literally often corresponds to that, in real Indonesian usage noun + itu can also refer to something already known or identifiable, which may sound like English the.

So depending on context, perjanjian itu might be understood as:

• that agreement
• the agreement

This is very common in Indonesian, and learners should not assume that itu always has to be translated as a strongly contrastive that.

A simple learner-friendly pronunciation is:

meh-nahn-dah-tah-ngah-nee

A few tips:

• ng is like the sound in English sing
• each vowel is usually pronounced clearly
• Indonesian stress is often fairly even compared with English, though many speakers give a little extra emphasis near the end

So the whole sentence can be said roughly as:

meh-REH-kah meh-nahn-dah-tah-NGAH-nee per-jahn-JEE-ahn EE-too

The exact accent varies, but saying each syllable clearly will already make you understandable.