Learn Hardcore Portuguese (Brazil): Daqui a uma hora, o show começará, então guarde seu ingresso e entre na fila. - In an hour, the concert will start, so put your ticket away and get in line.

Daqui a uma hora literally means “from here to one hour from now”, so it strongly emphasizes “starting now, counting one hour ahead.”
Em uma hora means “in an hour”, and is also correct in this context.

In everyday speech in Brazil, daqui a X tempo is extremely common when talking about time from now:

Daqui a pouco = in a bit / shortly
Daqui a três dias = in three days

You could say:

Daqui a uma hora, o show começará.
O show começará daqui a uma hora.
O show começará em uma hora.

All are correct; daqui a uma hora just sounds very natural and explicit for “one hour from now.”

Can Daqui a uma hora be placed at the end of the sentence instead of the beginning?

Yes. Word order here is flexible. These are all fine:

Daqui a uma hora, o show começará.
O show começará daqui a uma hora.
O show, daqui a uma hora, começará. (less common, a bit more formal / written)

Placing daqui a uma hora at the beginning often sounds like an announcement or instruction, which fits this context (like something you’d hear over a loudspeaker). Putting it after the verb is a bit more neutral:

O show começará daqui a uma hora.

Why is the future tense começará used? Don’t Brazilians usually say vai começar?

Both forms are correct:

O show começará. (simple future)
O show vai começar. (periphrastic future, with ir)

In Brazilian Portuguese:

vai começar is more common in everyday, informal speech.
começará sounds a bit more formal, neutral, or “announcement-like.”

For something like a public announcement or written instruction, começará fits very well. In casual conversation, you’d more likely hear:

Daqui a uma hora o show vai começar.

What exactly does show mean in Brazilian Portuguese? Is it any kind of show?

Show in Brazilian Portuguese is a loanword from English, but its use is narrower:

It usually means a live performance, especially concerts, music shows, or sometimes stand-up comedy or big entertainment events.

Examples:

Vou ao show da banda hoje. = I’m going to the band’s concert today.
O show começa às 20h. = The concert/show starts at 8 p.m.

For a more generic “performance” or “stage production,” you might also see:

espetáculo (performance/show)
apresentação (performance/presentation)

But show is extremely common in Brazil when talking about ticketed entertainment events like concerts.

What does ingresso mean here? How is it different from other words for “ticket” like bilhete or passagem?

In Brazil:

ingresso = a ticket for entering an event (show, movie, game, museum, etc.)
- ingresso do show = concert ticket
- ingresso do cinema = movie ticket

Other words:

bilhete = ticket, but more often:
- a small note / message (bilhete para você = a note for you)
- sometimes a lottery ticket (bilhete de loteria)
passagem = a travel ticket (bus, plane, train)
- passagem de ônibus, passagem de avião

So in this sentence, guarde seu ingresso specifically means “keep/hold on to your entry ticket for the show.”

Why is it guarde seu ingresso and not something like guarda seu ingresso?

Guarde is the imperative form for você (the standard “you” in Brazil). In Brazilian Portuguese:

For você, the affirmative imperative uses the present subjunctive form:
- guardar → (que você) guarde → guarde (imperative)
- entrar → (que você) entre → entre (imperative)

So:

Guarde seu ingresso. = (Você) keep your ticket.
Entre na fila. = (Você) get in line.

Guarda as an imperative is used with tu, which is regionally used (and increasingly informal):

(tu) guarda teu ingresso.
(tu) entra na fila.

But since você is the dominant pronoun in Brazil, guarde and entre are the normal polite/instructional forms.

Is guarde here a polite request or a strong order?

It’s an imperative, but in Brazilian Portuguese, using você-imperative (like guarde, entre) is the standard neutral way to give instructions, especially in:

announcements
written notices
signs
customer instructions

It doesn’t sound rude by itself. To make it feel even more polite, people might add por favor:

Guarde seu ingresso e entre na fila, por favor.

But even without por favor, in this context (probably an announcement), it feels normal and not aggressive.

What exactly does seu mean in seu ingresso? Does it ever mean “his/her/their” too?

Seu is a possessive that usually means “your” (for você), but it can also mean his, her, their, its depending on context:

seu ingresso = your ticket (talking to one person, você)
o ingresso dele = his ticket
o ingresso dela = her ticket
o ingresso deles/delas = their ticket

Yes, seu can be ambiguous and potentially mean “his/her/their,” but in this kind of direct instruction (“keep your ticket”), it’s clearly “your.”

To avoid ambiguity in other contexts, people often use:

o seu ingresso (still ambiguous, but often clear by context), or
o ingresso de você(s) is possible but sounds odd; usually we say:
- o ingresso de vocês = your (plural) ticket(s)
- o ingresso dele/dela for his/her

What does entrar na fila literally mean, and is it the usual way to say “get in line”?

Literally:

entrar = to enter
fila = line / queue
na = in the (contraction of em + a)

So entrar na fila = enter the line, i.e., get in line / join the queue.

This is a very common expression. Related phrases:

ficar na fila = stay/stand in line
pegar a fila or pegar a fila desde o começo = to get in line / start from the back of the line

In this context, entre na fila is a standard instruction: “Get in line.”

Why is it na fila and not em a fila or just em fila?

Portuguese commonly contracts the preposition em with the feminine article a:

em + a = na
em + as = nas
em + o = no
em + os = nos

So:

entrar em a fila → entrar na fila (correct and natural)
entrar em fila = “enter in line (formation),” which sounds more like “enter in a line/formation” rather than “get in the line.”

For a specific, known line/queue (like at a venue), na fila is the normal form: entre na fila.

What does então do in this sentence? Is it like “so” or “then” in English?

Yes, então here works like “so / then / therefore”, connecting the two ideas:

Daqui a uma hora, o show começará, então guarde seu ingresso e entre na fila.
- “In an hour the show will start, so keep your ticket and get in line.”

Uses of então:

As a conjunction (like here), meaning:
- so, therefore, then
  Example:
  Está chovendo, então leve um guarda-chuva. = It’s raining, so take an umbrella.
As a conversational filler:
- Então… at the beginning of a sentence = “So…” (to start or resume a topic)

In this sentence it’s clearly the first use: a logical consequence.

Is the comma before então necessary? Could we write this as two sentences?

You have some options:

With a comma before então (as given):
- Daqui a uma hora, o show começará, então guarde seu ingresso e entre na fila.
With a period, making two sentences:
- Daqui a uma hora, o show começará. Então, guarde seu ingresso e entre na fila.

Both are acceptable. Splitting into two sentences can make the instructions clearer, especially in signage or formal writing.

The comma before então in a single sentence is common because it separates two clauses: one states a fact, the other gives a resulting instruction.

How formal or informal does this whole sentence sound in Brazilian Portuguese?

The sentence is neutral-to-formal, which is ideal for:

public announcements
event instructions
written notices

Details that add to that tone:

use of começará instead of vai começar
guarde / entre (você-imperative, not slangy)
clear, standard vocabulary (ingresso, fila, então)

For a more casual tone among friends, someone might say:

Daqui a uma hora o show vai começar, então guarda o ingresso e entra na fila.
(using vai começar, guarda, entra, and probably dropping some commas)

But for a sign or loudspeaker announcement, the original sentence is very natural and appropriate.