Neste canal, o volume fica muito alto quando começa o filme.

Neste is a contraction of em + este.

• em = in, on, at
• este = this

So neste canal means something like in/on this channel.

Portuguese very often combines prepositions with demonstratives, so instead of saying em este, you normally say neste.

Other common contractions like this are:

• nesse = em
  • esse
• naquele = em
  • aquele

Both can often be translated as in/on this/that, but the basic distinction is:

• este / neste: closer to the speaker, or sometimes something being introduced right now
• esse / nesse: closer to the listener, or something already mentioned

In everyday Brazilian Portuguese, many speakers do not keep this distinction very strictly, and nesse is often more common in casual speech. Still, neste is completely correct and natural.

So in this sentence, neste canal suggests on this channel here or simply on this channel.

Yes. In this context, canal almost certainly means a TV channel.

So Neste canal means On this channel.

Portuguese canal can also mean a physical canal, but the context here clearly points to television.

Portuguese uses definite articles much more often than English.

So where English might say:

• Volume gets very loud

Portuguese naturally says:

• O volume fica muito alto

The article o does not necessarily mean a very specific one in the English sense. It is just the normal way Portuguese refers to many nouns in general or in a familiar context.

Here ficar means to become, to get, or to end up being.

So:

• o volume fica muito alto = the volume gets very loud

This is different from:

• é muito alto = it is very loud as a more general characteristic
• está muito alto = it is very loud right now, in its current state

Using fica suggests a change happens: the volume was at one level, and then it becomes louder.

That matches the rest of the sentence well, because the change happens when the movie starts.

Yes, alto often means high or tall, but with sound or volume it means loud.

Examples:

• o preço está alto = the price is high
• ele é alto = he is tall
• o som está alto = the sound is loud
• o volume está alto = the volume is loud/high

So in this sentence, muito alto means very loud.

Because alto agrees with volume, and volume is a masculine noun in Portuguese:

• o volume
• therefore alto

If the noun were feminine, the adjective would change:

• a música está alta

So the adjective must match the gender and number of the noun it describes.

In muito alto, muito is working as an adverb meaning very, so it does not change.

• muito alto = very loud
• muito baixa = very low/quiet

But when muito is an adjective or quantity word meaning many/much, it does change:

• muito volume = a lot of volume
• muita música = a lot of music
• muitos canais = many channels
• muitas propagandas = many commercials

So here, because it means very, muito stays the same.

Both are correct.

• quando começa o filme
• quando o filme começa

In Portuguese, especially after words like quando, aqui, ali, and similar expressions, it is common to put the verb before the subject. This is called inversion.

So quando começa o filme is a natural and common word order, especially in spoken and everyday Portuguese.

There is little difference in meaning here. If anything:

• quando o filme começa may feel a bit more neutral or straightforward
• quando começa o filme may sound a bit more flowing or idiomatic in this structure

Both fica and começa are in the present indicative:

• fica = from ficar
• começa = from começar

They are in the present because the sentence describes a habitual or general situation, not a one-time event.

It means something like:

• Whenever the movie starts, the volume gets very loud on this channel

Portuguese, like English, often uses the present tense for repeated situations and general truths.

The subject of fica is o volume.

So the structure is:

• Neste canal = location/topic
• o volume = subject
• fica muito alto = verb + description
• quando começa o filme = time clause

A useful way to see it is:

• On this channel, the volume gets very loud when the movie starts.

The channel is not what gets loud; the volume is.

The comma is natural and helpful because Neste canal is an introductory phrase.

It separates the setting from the main statement:

• Neste canal, o volume fica muito alto...

Without the comma, the sentence would still probably be understood, but the comma makes it clearer and more natural in writing.

So this punctuation is a good model to follow.

Yes, you could, but the nuance is slightly different.

• o volume fica muito alto focuses on the volume level
• o som fica muito alto focuses more generally on the sound

In many everyday situations, both would be understood. But o volume is especially appropriate if you are talking about the loudness setting or how loud the audio becomes.