Kakabukas lang ni Liza ng kurtina dahil mainit sa kwarto.

It means just opened or has just opened.

This is a special Filipino pattern:

• kaka- + verb root = an action that was completed very recently
• lang = just / only

So kakabukas lang gives the idea of something that happened only a moment ago.

Compare:

• Nagbukas si Liza... = Liza opened...
• Kakabukas lang ni Liza... = Liza has just opened... / Liza just opened...

No. They are spelled the same, but they are different words.

In this sentence, bukas is the verb root related to opening.

Why we know that:

• it appears in the form kakabukas, which is a verbal pattern
• the sentence is about opening a curtain

So here kakabukas cannot mean anything related to tomorrow.

Because the kaka- recent-completed construction usually marks the doer with the genitive marker:

• ni for a personal name
• ng for a common noun

So ni Liza marks Liza as the one who did the action.

This is different from a more ordinary verbal sentence like:

• Nagbukas si Liza ng kurtina.

There, si Liza is used. But with kakabukas, ni Liza is the normal pattern.

ng kurtina marks the thing affected by the action: the curtain.

So in the sentence:

• ni Liza = the doer
• ng kurtina = the thing opened

Also note the difference:

• ni is used with personal names
• ng is used with common nouns

So you get:

• ni Liza
• ng kurtina

Here, lang adds the idea of just.

So:

• kakabukas ni Liza ng kurtina = Liza has recently opened the curtain
• kakabukas lang ni Liza ng kurtina = Liza has just opened the curtain

It emphasizes how recent the action is.

Also, lang is the short everyday form of lamang.

Because Filipino often uses predicate-first word order.

That means the action or description often comes first, and the actor comes later.

So this order is very natural:

• Kakabukas lang ni Liza ng kurtina...

Instead of an English-style order like:

• Liza has just opened...

Filipino does not need to copy English word order.

Dahil means because.

It introduces the reason:

• dahil mainit sa kwarto = because it is hot in the room

So the whole sentence gives an action and then its reason:

• Liza has just opened the curtain
• because it is hot in the room

A very common more conversational alternative is kasi, but dahil is perfectly normal and slightly more neutral or formal.

Because Filipino often does not use a present-tense verb like is in this kind of sentence.

• mainit = hot
• sa kwarto = in the room

So mainit sa kwarto naturally means:

• it is hot in the room
• or the room is hot

Filipino can express this idea without adding a separate word for is.

sa is a marker often used for location, direction, or place.

So:

• sa kwarto = in the room

Here it tells you where the heat is being experienced.

You can think of sa here as similar to in or at, depending on context.

Also, kwarto means room.

Yes, you could, but the nuance changes.

• Nagbukas si Liza... = Liza opened...
• Kakabukas lang ni Liza... = Liza has just opened... / Liza just opened...

So kakabukas lang specifically highlights that the action happened very recently.

If you want to stress just now, the original sentence is better.