Dia mengubah posisi meja.

Yes. Dia can mean either he or she. Indonesian does not normally mark gender in third-person singular pronouns.

So Dia mengubah posisi meja could mean:

• He changed the position of the table
• She changed the position of the table

You need context to know which one is meant.

Ubah is the root word meaning change.
Mengubah is the active verb form built with the prefix meN-.

This prefix is very common in Indonesian and often marks an active verb, especially when it takes a direct object.

• ubah = change / to change
• mengubah = to change something

In this sentence, the speaker is talking about changing a specific thing, namely posisi meja, so mengubah is the natural form.

It comes from:

• meN-
  • ubah → mengubah

The prefix meN- changes shape depending on the first sound of the root. Before a vowel like u, it often becomes meng-.

So:

• ubah → mengubah

This is a very common pattern in Indonesian verbs.

Posisi meja means the table’s position or the position of the table.

It is a noun phrase:

• posisi = position
• meja = table

So the thing being changed is not the table itself directly, but its position.

Because Indonesian usually does not use a separate word like of in this kind of phrase.

Instead, Indonesian often puts the main noun first and the describing noun after it:

• posisi meja = position of the table
• literally: position table

This pattern is very common:

• warna mobil = the color of the car
• nama orang itu = that person’s name

So posisi meja is completely normal Indonesian structure.

The sentence follows the common Indonesian word order:

• Dia = subject
• mengubah = verb
• posisi meja = object

So it is:

Subject + Verb + Object

That is very similar to English:

• She changed the table’s position

By itself, meja does not explicitly show singular or plural.

So grammatically, Indonesian nouns are often neutral about number unless context makes it clear. In this sentence, most people would naturally understand meja as the table or a table, singular, because that is the most likely reading.

If you wanted to make it clearly plural, you could say:

• meja-meja = tables

But in normal speech, context usually does the job.

Yes, posisi is a common word, and it is understandable here. It is somewhat formal or neutral in tone.

A very common alternative in everyday Indonesian is letak:

• Dia mengubah letak meja.

That also means He/She changed the position of the table.

Another very common option is:

• Dia memindahkan meja. = He/She moved the table.

This version focuses more directly on moving the table itself.

They are similar, but not exactly the same.

• Dia mengubah posisi meja = He/She changed the table’s position
  • focus: the position changed
• Dia memindahkan meja = He/She moved the table
  • focus: the action of moving the table

In many situations, they describe the same real-world event. But memindahkan meja is often the more natural everyday way to say it if someone physically moved a table.

Sometimes, yes, if the subject is already clear from context.

For example:

• Mengubah posisi meja.

This could appear in notes, instructions, or informal context, but by itself it feels incomplete as a normal standalone sentence in many situations.

If you want a full neutral sentence, keeping dia is better:

• Dia mengubah posisi meja.

You use tidak before the verb:

• Dia tidak mengubah posisi meja.

This means:

• He/She did not change the position of the table

A useful pattern is:

• dia
  • tidak
    • verb

A simple way is to use question intonation:

• Dia mengubah posisi meja?

Another clearer way is:

• Apakah dia mengubah posisi meja?

This means:

• Did he/she change the position of the table?

Apakah is a common question marker for yes/no questions.

A rough pronunciation guide is:

• Dia → dee-ah
• mengubah → muhng-oo-bah
• posisi → po-see-see
• meja → may-jah

Very roughly together:

• dee-ah muhng-oo-bah po-see-see may-jah

A couple of helpful notes:

• ng in mengubah sounds like the ng in sing
• j in meja sounds like English j in job

It can sound slightly formal or less direct, depending on the situation.

If someone physically moved a table in a room, many speakers would more naturally say:

• Dia memindahkan meja.

But Dia mengubah posisi meja is still correct, especially if you want to emphasize the idea of changing its position rather than just the act of moving it.