A coleta seletiva é amanhã.

Because coleta is a feminine singular noun, and Portuguese normally uses a definite article with specific scheduled events or known things.

• a coleta = the collection / the pickup
• seletiva agrees with coleta, so it is also feminine singular.

In Portuguese, using the article here sounds natural. Leaving it out would usually sound incomplete or unnatural in this context.

In Brazilian Portuguese, coleta seletiva usually refers to the separate collection of recyclable waste, often done by the city or a building service.

So it is not just collecting in a general sense. It usually means a specific recycling pickup system where trash is sorted by type.

Portuguese uses ser in expressions that identify when something happens:

• A reunião é amanhã.
• O jogo é domingo.
• A coleta seletiva é amanhã.

Here, é is linking the event to its scheduled time.
Using está amanhã would be incorrect.

A useful shortcut:

• use ser for when an event is
• use estar more for location, condition, or temporary states

Because Portuguese does not need a preposition here.

English says It is on Friday or sometimes just It is Friday, but Portuguese commonly says:

• É amanhã
• É segunda-feira
• É hoje

So amanhã can appear directly after é with no extra word.

Yes. Será amanhã is grammatically correct.

The difference is mainly one of style:

• A coleta seletiva é amanhã. = very common, direct, natural in everyday speech
• A coleta seletiva será amanhã. = a bit more formal or explicit about the future

Both are correct, but é amanhã is especially common for scheduled events.

Because in Portuguese, adjectives often come after the noun.

So:

• coleta seletiva
• lixo reciclável
• energia solar

Some adjectives can come before the noun, but the normal pattern is noun + adjective.
In this case, seletiva describes the type of collection.

There is feminine singular agreement in the noun phrase:

• a = feminine singular article
• coleta = feminine singular noun
• seletiva = feminine singular adjective

That is why it is:

• a coleta seletiva

and not:

• o coleta seletivo
• a coleta seletivo

The verb é stays the same because it agrees with the subject as a whole, which is singular.

Yes, it is natural. It sounds like a normal way to say that the recycling pickup is scheduled for tomorrow.

Depending on the region or situation, people might also say:

• A coleta seletiva passa amanhã.
• Tem coleta seletiva amanhã.
• Amanhã tem coleta seletiva.

These alternatives are also common in everyday Brazilian Portuguese.
The original sentence is clear and correct, just slightly more neutral and straightforward.

Yes. You can say:

• Amanhã é a coleta seletiva.

This is also correct, but it changes the focus a little.

• A coleta seletiva é amanhã. focuses first on the recycling pickup
• Amanhã é a coleta seletiva. focuses first on tomorrow

In conversation, word order often changes depending on what the speaker wants to emphasize.

A natural pronunciation is roughly:

a co-LE-ta sele-TCHI-va é a-ma-NYÃ

A few useful notes:

• coleta stress: le
• seletiva stress: ti
• in many Brazilian accents, ti before a vowel sounds like tchi
• amanhã has nasal sound at the end
• é amanhã may sound smoothly connected in speech, almost like éamanhã

You do not need to pronounce every word separately in a rigid way; natural Brazilian speech links them smoothly.

Yes. Coleta is a general noun meaning collection or gathering, depending on context.

For example:

• coleta de dados = data collection
• coleta de sangue = blood collection
• coleta de lixo = garbage collection

What makes it specifically about recycling here is seletiva. That adjective gives the idea of sorted or selective collection.