Ilagay mo ang halaman sa tabi ng bintana.

Lagay is the root word meaning place or put.
Ilagay is the conjugated verb form used for put/place something.

In this sentence, ilagay is being used as a command, so it works like put in English:

• Ilagay mo ang halaman... = Put the plant...

This form also tells you something about the grammar: it is a patient-focus form, which means the thing being acted on is treated as the main noun in the sentence.

This is a very common question, because both mo and ka can relate to you.

In Filipino, the choice depends on the verb pattern.

• With actor-focus verbs, you often use ka.
• With patient-focus verbs like ilagay, the doer is marked with mo.

So:

• Ilagay mo ang halaman... = You put the plant...
• but
• Maglagay ka ng halaman... = a different verb pattern, so it uses ka

So mo here does mean you, not your.

Because halaman is the noun being highlighted as the main thing affected by the action.

With ilagay, the thing being put takes ang. So:

• ang halaman = the plant, as the main noun of the sentence

This is why the sentence is structured as:

• Ilagay mo ang halaman...

not

• Ilagay mo ng halaman...

Using ang here matches the patient-focus verb ilagay.

Usually, yes in this context.

Filipino does not have English-style articles that match exactly with the and a/an. But ang often makes a noun sound specific, so ang halaman is very naturally understood as the plant.

If you wanted a plant, you would more likely say something like:

• isang halaman

So in this sentence, ang halaman is best understood as the plant.

Sa tabi ng means beside, next to, or more literally at the side of.

Breakdown:

• sa = at / in / on / to
• tabi = side
• ng bintana = of the window

So literally:

• sa tabi ng bintana = at the side of the window

Natural English:

• beside the window
• next to the window

Here, ng links tabi and bintana.

• tabi = side
• ng bintana = of the window

So:

• tabi ng bintana = side of the window

This is one of the common uses of ng in Filipino: it can mark a kind of of relationship.

So in this sentence, ng is not there randomly; it is part of the expression meaning the side of the window.

Because sa bintana and sa tabi ng bintana do not mean exactly the same thing.

• sa bintana = at the window / to the window / on the window, depending on context
• sa tabi ng bintana = beside the window / next to the window

If you want the specific idea of next to the window, sa tabi ng bintana is the clearer phrase.

No, Filipino word order is fairly flexible.

The given sentence is very natural:

• Ilagay mo ang halaman sa tabi ng bintana.

But you could also say:

• Ilagay mo sa tabi ng bintana ang halaman.

Both are grammatical. The difference is mostly about flow or emphasis.

• Putting ang halaman earlier can keep the plant as the more immediate focus.
• Putting sa tabi ng bintana earlier can emphasize the location a bit more.

English is much stricter about word order than Filipino.

Yes, this is a command.

To make it more polite, you can add po:

• Ilagay mo po ang halaman sa tabi ng bintana.

If you are speaking formally or to more than one person, you can use ninyo:

• Ilagay ninyo ang halaman sa tabi ng bintana.
• Ilagay po ninyo ang halaman sa tabi ng bintana.

You can also soften it with paki-:

• Pakilagay po ang halaman sa tabi ng bintana.

That sounds more like Please put the plant beside the window.

They are similar in general idea, but the grammar and emphasis are different.

• Ilagay mo ang halaman sa tabi ng bintana
  This treats the plant as the main thing being acted on. It sounds very natural when a specific plant is already known.

• Maglagay ka ng halaman sa tabi ng bintana
  This uses an actor-focus verb. It focuses more on the doer, and ng halaman is not the main noun in the same way. It can sound more like Put a plant beside the window or Place a plant beside the window, especially if the plant is not yet specific.

So if you mean that specific plant, Ilagay mo ang halaman... is the better fit.