Kapag tuyo na ang sahig sa banyo, papasok na si Maria para maligo.

Here, kapag means when or once in a condition that is expected to happen.

So:

Kapag tuyo na ang sahig sa banyo, papasok na si Maria...
= When/Once the bathroom floor is dry, Maria will go in...

A useful contrast:

• kapag = for a condition/event seen as expected or tied to a future result
• kung = often if, and can also mean whether

In many everyday sentences, English if may be translated by either kapag or kung, but kapag often sounds more like when/once this happens.

Because Filipino very often uses predicate-first word order.

In this clause:

• tuyo na = the predicate/state
• ang sahig sa banyo = the thing being described

So the structure is literally closer to:

Dry already the floor in the bathroom

That sounds odd in English, but it is normal in Filipino.

You could also say:

Ang sahig sa banyo ay tuyo na.

That is grammatical too, but it is a different word order. The version in your sentence is very natural and common.

Tuyo means dry.

The particle na here adds the sense of:

• already
• now
• at this point

So tuyo na means:

• already dry
• dry now
• has become dry

In this sentence, it suggests a change of state: the floor was wet before, and now it is dry.

The two na particles are related in feeling, but they are doing slightly different jobs.

1. tuyo na

Here, na marks a new state or completed change:

• tuyo = dry
• tuyo na = dry now / already dry

2. papasok na

Here, na suggests that the action will happen now, already, or at that point:

• papasok = will go in / will enter
• papasok na = will go in now / will enter then / is about to go in

So the sentence has a nice sequence:

• first, the floor becomes dry
• then, Maria goes in

Because Filipino uses different markers for different kinds of nouns.

ang

Used for a common noun that is the topic or subject-like noun of the clause:

• ang sahig = the floor

si

Used for a person's name:

• si Maria = Maria

So:

• ang sahig = the floor
• si Maria = Maria

This is a very common pattern:

• ang bata = the child
• si Ana = Ana

Sa is a very common marker for location, direction, or place-related relationships.

Here:

• sahig = floor
• sa banyo = in the bathroom / of the bathroom in context

So ang sahig sa banyo means:

• the floor in the bathroom
• more naturally in English, the bathroom floor

Filipino often uses a sa + place phrase after a noun to describe where that noun is.

Papasok comes from the root pasok, which is related to entering or going in.

This verb belongs to the -um- verb pattern. A useful set is:

• pumasok = entered / went in
• pumapasok = is entering / goes in regularly
• papasok = will enter / will go in

So papasok is the contemplated/future form.

Even though English may say enter, go in, or sometimes come in, the best translation depends on context. Here, papasok means Maria will go into the bathroom.

Because the location is already clear from context.

The first clause mentions the floor in the bathroom, and the second clause says Maria will go in to bathe. So listeners naturally understand that she is going into the bathroom.

A fuller version like this would also work:

Kapag tuyo na ang sahig sa banyo, papasok na si Maria sa banyo para maligo.

But repeating sa banyo is unnecessary, so the original sentence sounds more natural.

Para introduces purpose.

So:

• para = for / in order to / so that
• maligo = to bathe / to take a bath

Together:

para maligo = in order to bathe / to take a bath

This is a very common Filipino pattern:

• umalis siya para bumili ng pagkain = he/she left to buy food
• dumating ako para tumulong = I arrived to help

So in your sentence, Maria is going in for the purpose of bathing.

Because after para, Filipino commonly uses the verb in a basic infinitive-like form.

For ligo, the forms are:

• naligo = bathed / took a bath
• naliligo = bathing / is taking a bath
• maliligo = will take a bath
• maligo = to bathe / take a bath

So after para, maligo is the natural choice:

• para maligo = to bathe

This is similar to English using to + verb.

Both are grammatical, but papasok na si Maria is more natural in ordinary Filipino.

Filipino often prefers predicate first:

• papasok na si Maria

You can also say:

• Si Maria ay papasok na

The version with ay is usually more formal, more written, or more emphatic in style. In everyday speech, the version without ay is very common.

The core idea is go in / enter.

The exact English translation depends on point of view:

• enter
• go in
• sometimes come in

In this sentence, papasok most naturally means go in or enter, because Maria is going into the bathroom.

So all of these can fit depending on translation style:

• Maria will go in to bathe
• Maria will enter to take a bath
• Maria will go into the bathroom to bathe

Very often, yes: kapag commonly introduces a condition or event that is expected to happen, and the main clause usually refers to what will happen after that.

In your sentence:

• Kapag tuyo na ang sahig sa banyo = once the floor is dry
• papasok na si Maria = Maria will then go in

So the whole sentence points forward in time.

That said, the verb or predicate after kapag does not always have to look like an obvious future form. Here, tuyo na is a state, not a future-marked verb, but the overall meaning is still future-oriented: the floor will be dry first, then Maria will enter.

Yes, in casual speech and informal writing, kapag is often shortened to pag.

So you may hear:

Pag tuyo na ang sahig sa banyo, papasok na si Maria para maligo.

That is very natural in conversation.

In more careful or standard writing, kapag is often preferred. Both are common; kapag is just the fuller form.