Na montra da papelaria, vi um cartaz de liquidação.

Na is a contraction of em + a.

• em = in / on / at
• a = the (feminine singular)

So:

• na montra = in the shop window / in the display window

Portuguese very often contracts prepositions with articles, so em a montra would be wrong here. You must say na montra.

Da is the contraction of de + a.

• de = of / from
• a = the (feminine singular)

So:

• a montra da papelaria = the shop window of the stationery shop

This is the normal way to link the two nouns. Portuguese often uses de where English uses possession:

• a porta da casa = the door of the house / the house’s door
• a montra da papelaria = the stationery shop’s window

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

It refers to the window at the front of a shop where products, signs, or advertisements are displayed.

A useful Portugal/Brazil note:

• In Portugal, montra is very common.
• In Brazil, people more often say vitrine.

So if you are learning Portuguese from Portugal, montra is the natural word here.

Papelaria is a stationery shop, meaning a shop that sells things like:

• paper
• notebooks
• pens
• school supplies
• office supplies

Depending on the shop, it may also sell cards, magazines, small gifts, or printing-related items.

So papelaria is not just a place that sells paper; it is a general stationery-type shop.

Vi is the 1st person singular preterite of the verb ver (to see).

So:

• eu vi = I saw

In this sentence, vi tells you that the speaker is talking about one completed action in the past: they saw the sign.

A quick comparison:

• vi = I saw (completed event)
• via = I used to see / I was seeing (ongoing or habitual past)

So vi is the right form for a simple past event.

Portuguese often leaves out subject pronouns when the verb ending already makes the subject clear.

Here:

• vi already clearly means I saw

So Eu vi is possible, but just vi is very natural and common.

Portuguese does this much more than English. English usually needs the subject pronoun, but Portuguese often does not.

This is a very common Portuguese noun structure:

• um cartaz = a poster / sign
• de liquidação = for clearance / about a clearance sale

So um cartaz de liquidação means something like:

• a clearance sign
• a poster advertising a clearance sale

The de + noun pattern is extremely common in Portuguese for describing the type or purpose of something:

• um copo de água = a glass of water
• uma loja de roupa = a clothing shop
• um cartaz de liquidação = a clearance poster/sign

Um means a / an, while o means the.

So:

• vi um cartaz = I saw a sign (an unspecified sign)
• vi o cartaz = I saw the sign (a specific sign already known in the context)

Here, um is used because the sentence is introducing the sign as new information, not referring back to a specific one already mentioned.

Yes, both are natural.

1. Na montra da papelaria, vi um cartaz de liquidação.
   This puts the location first, as a setting or topic.

2. Vi um cartaz de liquidação na montra da papelaria.
   This starts with the action and sounds slightly more neutral.

The first version gives a little more emphasis to where the sign was. Portuguese often moves location phrases to the front like this.

The comma separates the fronted location phrase from the main clause:

• Na montra da papelaria, = setting/location
• vi um cartaz de liquidação. = main action

This kind of comma is common when a sentence begins with a longer adverbial phrase. It helps readability and marks a slight pause.

In some short sentences, Portuguese punctuation can be flexible, but here the comma is perfectly natural.

Not exactly.

In Portugal Portuguese, liquidação usually suggests a clearance sale, often with the idea of getting rid of stock, sometimes at the end of a season or when a shop is closing out items.

It is not always the same as every kind of sale or discount event.

Useful comparisons:

• liquidação = clearance sale
• promoção = promotion / special offer
• saldos = sales (especially seasonal sales)

So cartaz de liquidação has a more specific feel than just any discount sign.

Yes. In this kind of sentence, na montra naturally means the poster was in the display window, meaning it was visible there as part of the shop display.

Portuguese often uses em / na in a broad way for location, where English might choose between:

• in the window
• on display in the window
• in the shop window

So na montra is the normal and idiomatic choice.

Not necessarily.

Cartaz can mean:

• a poster
• a notice
• a sign
• an advertising placard

In a shop-window context, it often refers to a sign or poster announcing something, such as a sale or promotion.

So in this sentence, depending on the exact situation, English could translate it as:

• a poster
• a sign
• a sale sign

The nouns are:

• montra — feminine
• papelaria — feminine
• cartaz — masculine
• liquidação — feminine

This matters because articles and contractions must agree with the noun:

• na montra = em + a because montra is feminine
• da papelaria = de + a because papelaria is feminine
• um cartaz because cartaz is masculine

Getting the gender right is important because it affects articles, adjectives, and many contractions in Portuguese.

If you used the imperfect, you would get via:

• Na montra da papelaria, via um cartaz de liquidação.

Grammatically possible, but it would usually mean something different, such as:

• I used to see a clearance sign in the shop window
• I was seeing a clearance sign in the shop window

That is less natural as an isolated sentence, because seeing a sign is normally treated as a simple completed event. That is why vi works better here.