Entriamo adesso, altrimenti il parco divertimenti chiude.

It can mean either, depending on context.

Entriamo is the 1st person plural present of entrare = to enter / to go in.

In this sentence, it most naturally means:

• we’re going in now
• or let’s go in now

Italian often uses the present tense for immediate actions and suggestions. So Entriamo adesso can sound like a decision being made right now.

Because Italian usually doesn’t need subject pronouns unless they are being emphasized.

The ending -iamo already tells you the subject is we.

So:

• Entriamo = we enter / we’re going in / let’s go in
• Noi entriamo would add emphasis, like we are the ones going in

Leaving out the pronoun is completely normal in Italian.

Adesso means now.

It is very close in meaning to ora, and in many situations they are interchangeable:

• Entriamo adesso
• Entriamo ora

Both mean Let’s go in now / We’re going in now.

Very generally:

• adesso can feel a little more like right now / at this moment
• ora is also now, and is extremely common

In this sentence, adesso stresses the urgency a bit nicely.

Altrimenti means otherwise.

It introduces the consequence of not doing the first action:

• Entriamo adesso, altrimenti il parco divertimenti chiude.
• Let’s go in now, otherwise the amusement park closes / will close.

It commonly appears before the result or consequence, just like otherwise in English.

You could also find it in slightly different positions depending on style, but this placement is very natural.

Because Italian often uses the present tense to talk about the near future, especially when the event is expected or scheduled.

So chiude literally means closes, but here it can naturally mean:

• is closing
• will close

This is very common in Italian:

• Domani parto. = I’m leaving tomorrow.
• Il negozio chiude alle otto. = The shop closes / will close at eight.

So in your sentence, chiude sounds completely normal.

Yes, it could.

• ...altrimenti il parco divertimenti chiude
• ...altrimenti il parco divertimenti chiuderà

Both are possible.

The version with chiude is very natural in everyday Italian because it refers to something expected or scheduled.
The version with chiuderà sounds a bit more explicitly future-oriented.

In many everyday situations, Italians prefer the present tense where English might prefer will.

Italian often uses the definite article where English may or may not use the.

Here, il parco divertimenti means the amusement park.

If the speaker and listener both know which park they are talking about, the article is completely natural.

Also, parco divertimenti is the standard expression for amusement park:

• parco = park
• divertimenti = amusements / entertainments

Together: amusement park.

Because the fixed expression is parco divertimenti, literally something like park of amusements / entertainment activities.

Even though English says amusement park with a singular noun, Italian uses this set phrase with divertimenti in the plural.

So you should learn parco divertimenti as one vocabulary unit.

Yes.

Entrare often works on its own when the place is obvious from context.

For example:

• Entriamo. = Let’s go in.
• Posso entrare? = Can I come in?

If needed, Italian can also specify the place:

• entrare nel parco = to enter the park
• entrare in casa = to go into the house

In your sentence, the place is understood from il parco divertimenti in the second part.

In this context, it usually sounds more like a suggestion or decision:

• Let’s go in now

That’s because the second part gives a reason:

• otherwise the amusement park closes

So the speaker is urging action.

Grammatically, though, it is still just the present tense we enter / we are entering, and Italian often lets context show whether it is a statement or a suggestion.

Not with exactly the same meaning.

• Entriamo adesso = Let’s go in now / Let’s enter now
• Andiamo adesso = Let’s go now / We’re leaving now

Entrare specifically focuses on going inside.
Andare just means to go.

So if you want the idea of entering the amusement park, entriamo is the better choice.

Because the sentence has two linked parts:

• Entriamo adesso
• altrimenti il parco divertimenti chiude

The comma helps separate the main statement from the consequence introduced by altrimenti.

This is very natural punctuation in Italian, just as in English:

• Let’s go in now, otherwise the amusement park will close.

It is neutral everyday Italian.

Nothing in it is especially formal or especially casual. It is exactly the kind of sentence someone might say in normal conversation.

The verb form entriamo includes the speaker and listener together, so it feels direct and natural in spoken language.