Пойдём, если только плата за вход не окажется высокой.

It can suggest both, depending on context.

Grammatically, пойдём is the 1st person plural future of пойти (to go, perfective). So literally it is we will go.

However, in Russian, this form is also very commonly used to make a suggestion, so it can sound like:

• we’ll go
• let’s go

In this sentence, because it is followed by a condition, it often feels like:

• We’ll go, unless the entrance fee turns out to be high.

So the form is future, but in natural use it can also carry the idea of a proposal or decision.

Russian often contrasts imperfective and perfective verbs.

• идти = to be going / to go, focusing on the process
• пойти = to set off / to go, focusing on the single action or result

Here the speaker means a single future action: going there if the condition is met. That is why Russian uses the perfective пойти, giving пойдём.

If you used идти, it would not fit this meaning as naturally in standard Russian.

Если только is a fixed expression. In many contexts it means something like:

• unless
• except if
• only if

In this sentence, together with не, it gives the sense:

• unless the entrance fee turns out to be high

So the whole pattern если только ... не ... often corresponds to English unless.

This is one of those places where Russian and English structure the idea differently.

Russian often uses:

• если только X не ...

to mean:

• unless X ...

So не is part of the normal Russian pattern here. It does not simply mean ordinary negation in the same way you might expect word-for-word from English.

So:

• Пойдём, если только плата за вход не окажется высокой.

means:

• We’ll go, unless the entrance fee turns out to be high.

A learner should usually treat если только ... не ... as a chunk.

Окажется is the future form of оказаться, which often means:

• to turn out
• to prove to be
• to end up being

So не окажется высокой means:

• does not turn out to be high

This is more natural here than a simple verb meaning to be, because the speaker does not yet know the price. The idea is that they will find out later whether it is high.

Because окажется adds the idea of finding out the result.

Compare:

• будет высокой = will be high
• окажется высокой = will turn out to be high

In this sentence, the speaker is talking about a price that is not known yet. That is why оказаться is very natural: it expresses discovering how high it actually is.

Because after оказаться, a predicate adjective is very often put in the instrumental case.

So:

• высокая = nominative feminine singular
• высокой = instrumental feminine singular

Since плата is feminine singular, the adjective matches it in gender and number, but it appears in the instrumental because of the construction:

• оказаться высокой = to turn out to be high

This is a very common pattern in Russian:

• оказаться полезным = to turn out useful
• оказаться трудной = to turn out difficult
• оказаться правым = to turn out to be right

Плата is a feminine noun. Because of that:

• the adjective describing it must also be feminine
• in this sentence, the adjective is высокой, the feminine instrumental singular form

So the agreement is:

• плата → feminine singular
• высокой → feminine singular instrumental

If the noun were masculine or neuter, the adjective form would change accordingly.

Literally, it means:

• payment for entry

In natural English, that is usually:

• entrance fee
• admission fee
• entry fee

So:

• плата = payment / fee
• за вход = for entry

This is a normal Russian way to refer to the money you pay to get in somewhere.

After за in the sense of for, Russian uses the accusative case.

So here:

• за вход = for entry

The noun вход is masculine inanimate, and in the accusative singular it has the same form as the nominative singular. So it still looks like вход.

That is why nothing visibly changes, even though it is accusative.

Because если только плата за вход не окажется высокой is a subordinate clause introduced by если только.

Russian normally separates this kind of clause with a comma:

• Пойдём, если только ...

This is similar to English punctuation in a sentence like:

• We’ll go, unless ...

Yes. Russian word order is flexible, although the given version is neutral and natural.

The sentence:

• Пойдём, если только плата за вход не окажется высокой.

has a straightforward order:

• main verb first
• then the condition
• inside the condition: subject + negation + verb + adjective

You may see variations for emphasis, but the original is the most standard for a neutral statement.

Not always.

Depending on context, если только can mean different things, such as:

• if only
• unless
• provided that

But in the specific pattern used here, especially with не, it is best understood as:

• unless

So in this sentence, translating it as unless is the most natural choice.

Yes. A simpler alternative might be:

• Пойдём, если плата за вход не будет высокой.

This means roughly the same thing:

• We’ll go if the entrance fee isn’t high.

But the original sentence is a bit more idiomatic and nuanced because:

• если только ... не ... gives a more natural unless
• окажется adds the idea of turns out to be

So the original sounds more polished and native-like.