Learn Hardcore Portuguese (Portugal): Vende-se televisão usada neste bairro. - Used television for sale in this neighborhood.

It’s the passive/indefinite marker (often called the passive se). With a transitive verb like vender, it turns the sentence into something like “is/are sold,” i.e., a neutral “for sale” statement that doesn’t mention who sells.

Singular: Vende-se televisão usada = “A used TV is sold / Used TV for sale.”
Plural: Vendem-se televisões usadas = “Used TVs are sold / Used TVs for sale.” Compare with impersonal se (no explicit subject), where the verb stays singular: Vive-se bem neste bairro (“People live well in this neighborhood”). Here it’s clearly the passive se because there’s a thing being sold.

Why is the verb singular (vende), not plural (vendem)?

Because the postverbal subject is singular: televisão. In the passive se construction, the verb agrees with what’s being sold:

Vende-se televisão usada (singular thing)
Vendem-se televisões usadas (plural things)

Could I say Vendem-se televisões usadas neste bairro?

Yes—use that if you mean more than one TV is for sale. Make everything agree in the plural:

Vendem-se televisões usadas neste bairro. Using plural noun and adjective forces plural verb agreement.

Why is there no article before televisão? Shouldn’t it be uma televisão?

In ads and notices, Portuguese often drops the article to sound general and concise: Vende-se televisão usada. If you add the article, you change the nuance:

Vende-se uma televisão usada = one specific used TV is for sale.
Vende-se a televisão usada = the used TV (already known in context) is for sale. Much rarer.

How do I say “Used TVs for sale” versus “A used TV for sale”?

Generic/singular (common on signs): Vende-se televisão usada.
Explicit singular item: Vende-se uma televisão usada.
Plural/general: Vendem-se televisões usadas.
You can also use the “for sale” expression: Há televisões usadas à venda / Uma televisão usada está à venda.

Why does usada end in -a and not -o?

Agreement. Televisão is feminine singular, so the adjective must be feminine singular: usada. If you used a masculine noun like televisor, you’d say televisor usado; plural would be televisões usadas (fem. pl.) or televisores usados (masc. pl.).

Does televisão mean the device or the medium?

In Portugal, televisão commonly means the device (a TV set) and also the medium (“television” as in broadcasting). On a sign like this, it clearly means the device. Synonyms you might see:

televisor (more formal/technical, the device)
TV (informal abbreviation)
aparelho de televisão (device)

What does neste mean, and why that form?

Neste = em + este (“in this”). It’s a contraction used before masculine singular nouns:

neste bairro = “in this neighborhood” Other demonstratives:
nesse bairro = “in that neighborhood (near you)”
naquele bairro = “in that neighborhood (over there/previously mentioned)” Feminine forms: nesta rua, nessa zona, naquela área.

Can I change the word order?

Yes. Typical sign order is verb + se + noun. But you can move elements for emphasis:

Neste bairro, vendem-se televisões usadas.
Televisões usadas vendem-se neste bairro.
Vende-se, neste bairro, televisão usada. All are grammatical; the first is very natural in informative writing.

Why is there a hyphen in vende-se? Could I write se vende?

In European Portuguese, affirmative declaratives default to enclisis (pronoun after the verb) with a hyphen: vende-se. You switch to proclisis (se vende) only when something triggers it (e.g., negation, certain adverbs, relatives):

Não se vende televisão usada neste bairro.
Aqui se vendem televisões usadas. So, in your sentence (neutral, affirmative), vende-se is the standard form in Portugal.

How do I negate the sentence?

Place não before the clitic:

Singular: Não se vende televisão usada neste bairro.
Plural: Não se vendem televisões usadas neste bairro. Negation triggers proclisis (se before the verb) and you still keep agreement with the subject.

Is Vende-se televisão usada neste bairro natural in Portugal?

Yes. It’s perfectly natural as an ad/classified style sentence. On an actual sign stuck to the item, you might simply see Vende-se televisão usada (without the location) or the location separated: Vende-se televisão usada. Neste bairro.

Is there a more “neutral” way to say “for sale,” without se?

Yes:

à venda: Televisões usadas à venda neste bairro. / Há televisões usadas à venda neste bairro.
Explicit subject: Vendemos televisões usadas neste bairro. (We sell…) These avoid the se construction and are also common.

How do I pronounce the tricky parts in European Portuguese?

vende-se: roughly “VEN-de-sih” (the final e in se is a reduced vowel).
televisão: “te-le-vee-ZÃW” (final ão is a nasalized ‘ow’ sound).
bairro: “BAI-hoo” (the double r is a strong, breathy sound in many accents). These are approximations; listening to native audio will help nail the nasal ão and the reduced vowels.