Pela montra, dá para ver que a liquidação acaba hoje.

Pela montra means something like from the shop window/display, by looking at the display, or through the shop window.

Here, pela is the contraction of por + a. In this sentence, it suggests the window/display is the means or source of the information: by looking at it, you can tell that the sale ends today.

So it is not just talking about location; it is more like:

• from what you can see in the window
• judging by the display

In European Portuguese, montra usually means a shop window or window display.

It is the glass-front display where a shop shows products, signs, prices, or advertisements.

A learner should note:

• In Portugal, montra is the normal word.
• In Brazilian Portuguese, vitrine is much more common.

So this is a very European Portuguese word choice.

Dá para ver is a very common expression meaning:

• you can see
• it is possible to see
• one can tell

Literally, dar para + infinitive often means to be possible to... or to work for...

Examples:

• Dá para entrar? = Can you get in? / Is it possible to enter?
• Não dá para ouvir. = You can’t hear. / It’s not possible to hear.

So in your sentence, dá para ver que... means you can tell that...

Because dar para + infinitive is being used impersonally here.

In this kind of structure, dar often stays in the 3rd person singular:

• Dá para fazer isso.
• Não dá para esperar.
• Dá para ver daqui.

It does not agree with a visible subject in the way English verbs often do. It works a bit like saying:

• It’s possible to...
• You can...

So dá is the normal form here.

Because Portuguese often uses ver in contexts where English would use:

• see
• tell
• notice
• realize

So dá para ver que... can mean not only you can see that... literally, but also you can tell that... from the evidence.

That is very natural in Portuguese.

Que introduces the clause a liquidação acaba hoje.

So the structure is:

• dá para ver = you can see / one can tell
• que a liquidação acaba hoje = that the sale ends today

In English, that is often optional:

• You can see that the sale ends today
• You can see the sale ends today

In Portuguese, que is normally kept here.

Liquidação usually means a clearance sale or a sale to clear stock.

It is not always exactly the same as a general sale in English. It often suggests reduced prices because items are being cleared out.

Useful comparison:

• liquidação = clearance sale
• promoção = promotion / special offer
• saldos = seasonal sales / sale period

In everyday shop language in Portugal, saldos is also very common, but liquidação is perfectly natural and has a slightly more specific “stock-clearing” feel.

Portuguese often uses the present tense to talk about something scheduled or निश्चित for the near future.

So:

• A liquidação acaba hoje = The sale ends today

This is just like English, where we also often say:

• The sale ends today rather than
• The sale will end today

So the present tense is completely natural here.

It is placed first to set the scene or highlight the source of the information.

The sentence is basically saying:

• From the shop window/display, you can tell...

Putting Pela montra first emphasizes:

• where the evidence comes from
• what allows you to know this

A more neutral order would also be possible:

• Dá para ver pela montra que a liquidação acaba hoje.

Both are correct. The version with Pela montra first gives that phrase extra focus.

The comma is natural because Pela montra is a fronted introductory phrase.

It marks a small pause and helps readability:

• Pela montra, dá para ver que...

In informal writing, some people might omit it, especially in short sentences, but with this word order the comma is very normal.

So:

• Pela montra, dá para ver que... = very natural
• Pela montra dá para ver que... = possible, but less neatly punctuated

Because they do not mean the same thing.

• na montra = in the window/display
• pela montra = from/through/by means of the window/display

Compare:

• Há sapatos na montra. = There are shoes in the window.
• Pela montra, dá para ver que a loja está em saldos. = From the window display, you can tell the shop is having a sale.

So na montra would describe where something is, while pela montra explains how you know something.

Yes. Some natural alternatives are:

• Dá para ver pela montra que a liquidação acaba hoje.
• Vê-se pela montra que a liquidação acaba hoje.
• Pela montra, vê-se que a liquidação acaba hoje.

These are all similar in meaning.

A small nuance:

• dá para ver = it’s possible to see / you can tell
• vê-se = it can be seen / one sees

Both are natural, but dá para ver sounds especially conversational.