O aluguel é pago todo mês.

Aluguel is the noun rent in Brazilian Portuguese.

It is related to the verb alugar, which means to rent. In context, o aluguel usually means the rent payment or the rent amount.

Examples:

• O aluguel está caro. — The rent is expensive.
• Eu pago aluguel. — I pay rent.

Portuguese often uses the definite article o/a/os/as more than English does.

So o aluguel is the natural way to say the rent or just rent as the subject of the sentence. In English, we often drop the article, but in Portuguese it is very common to keep it.

So:

• O aluguel é pago todo mês. sounds natural.
• Aluguel é pago todo mês. is not the normal neutral way to say it.

Yes. É pago is the passive voice.

It is formed with:

• ser
  • past participle

So:

• é = is
• pago = paid

The sentence focuses on the rent, not on the person who pays it.

Active version:

• O inquilino paga o aluguel todo mês. — The tenant pays the rent every month.

Passive version:

• O aluguel é pago todo mês. — The rent is paid every month.

The verb pagar has two past participle forms:

• pagado — regular
• pago — irregular

In this sentence, after ser, Portuguese normally uses pago:

• O aluguel é pago todo mês.

Traditional grammar usually prefers:

• ser/estar
  • pago
• ter/haver
  • pagado

For example:

• A conta foi paga.
• Eu tinha pagado a conta.

In modern Brazilian Portuguese, many people also say:

• Eu tinha pago a conta.

But in your sentence, é pago is the standard and expected form.

Todo mês means every month.

Portuguese often uses todo/toda + singular noun to express regular frequency:

• todo dia — every day
• toda semana — every week
• todo mês — every month
• todo ano — every year

So the singular mês is completely normal here, just like English every month.

They are different:

• todo mês = every month
• todo o mês = the whole month / all month long

That little o changes the meaning.

Compare:

• O aluguel é pago todo mês. — The rent is paid every month.
• Ficou chovendo todo o mês. — It kept raining the whole month.

Yes.

All of these are possible:

• O aluguel é pago todo mês.
• O aluguel é pago todos os meses.
• O aluguel é pago mensalmente.

Nuance:

• todo mês — very natural, common in speech
• todos os meses — also very common, slightly fuller
• mensalmente — more formal or written

Pago agrees with aluguel, because aluguel is the subject.

Aluguel is masculine singular, so the participle is also masculine singular:

• o aluguel → pago

If the subject changes, the participle changes too:

• A conta é paga todo mês. — The bill is paid every month.
• Os impostos são pagos todo mês. — The taxes are paid every month.
• As contas são pagas todo mês. — The bills are paid every month.

No. The sentence does not say who pays it.

That is one of the main reasons to use the passive here: the action matters more than the person doing it.

If you want to include the person, you can add it:

• O aluguel é pago pelo inquilino todo mês. — The rent is paid by the tenant every month.

Without that, the sentence simply means that the rent gets paid monthly, with the payer left unspecified.

Yes. That is a very natural English equivalent.

Depending on style, you could translate it as:

• The rent is paid every month.
• The rent gets paid every month.

The first is a more direct match to the Portuguese structure.
The second sounds a little more conversational in English, but the idea is the same.