Vstup na swap je zdarma.

Here vstup means entry, admission, or access.

In this kind of sentence, it is often used the way English uses admission:

• Vstup je zdarma. = Admission is free.
• Zákaz vstupu. = No entry.

So vstup is not the act of physically stepping in only; it can also mean the right to enter an event or place.

Czech often uses na with events and activities.

So you say things like:

• jít na koncert = to go to a concert
• jít na festival = to go to a festival
• jít na kurz = to go to a course/class
• jít na swap = to go to a swap event

That is why vstup na swap means admission to the swap.

Using do would usually suggest going into a physical space or enclosed place:

• do domu = into the house
• do školy = to school / into the school building

So for an event, na swap is the natural choice.

Here swap is in the accusative, because na often takes the accusative when it means movement toward an event, place, or target.

Compare:

• Jdu na swap. = I’m going to the swap.
• Vstup na swap je zdarma. = Admission to the swap is free.

With many masculine inanimate nouns, the accusative looks the same as the nominative, so swap does not visibly change.

You may also see a different form in other contexts:

• na swapu = at the swap

That is locative, used when talking about location rather than direction/target.

Swap is a modern borrowing from English. In Czech, it usually refers to a swap event, often a place where people exchange clothes, books, plants, or other items.

So in everyday Czech, especially in event language, swap is quite common. It is especially common in urban, informal, or promotional contexts.

A more native-sounding Czech alternative might be something based on výměna (exchange), but swap is widely understood in the right context.

Zdarma means for free or free of charge.

In je zdarma, it works as a fixed expression meaning is free in the sense of costing nothing.

Important point: zdarma is not behaving like a regular adjective here, so it does not change for gender or number.

For example:

• Vstup je zdarma. = Admission is free.
• Nápoje jsou zdarma. = Drinks are free.
• Doprava je zdarma. = Delivery is free.

So even though English uses free like an adjective, Czech often uses zdarma as an adverbial/predicative expression.

This is a very useful distinction.

• zdarma = free of charge
• volný = free, available, unoccupied, unrestricted

So:

• Vstup je zdarma. = Admission costs nothing.
• Místo je volné. = The seat/place is free available.
• Dnes mám volno / jsem volný. = I’m free today.

If you said vstup je volný, that would usually mean something more like entry is open/unrestricted, not specifically free of charge.

So in your sentence, zdarma is the right choice.

Yes. Very often, especially on signs, posters, and websites, Czech leaves out je.

So both are possible:

• Vstup na swap je zdarma.
• Vstup na swap zdarma.

The version without je sounds more like a headline or notice. The version with je is a full sentence.

This is very common in announcements:

• Káva zdarma
• Doprava zdarma
• Vstup zdarma

This is another common learner question.

• vstup = entry, admission, access
• vstupné = admission fee, entrance fee

So:

• Vstup na swap je zdarma. = Admission to the swap is free.
• Vstupné je 100 Kč. = The admission fee is 100 CZK.

In real-life Czech, people sometimes use both in advertising-style language, but vstup is very natural in this sentence.

A useful contrast:

• Vstup zakázán. = Entry forbidden.
• Vstupné se neplatí. = There is no admission fee / no entry fee is charged.

Yes. Czech word order is flexible, and different versions can sound natural depending on emphasis.

For example:

• Vstup na swap je zdarma. = neutral
• Na swap je vstup zdarma. = emphasizes to the swap
• Zdarma je vstup na swap. = unusual, strongly marked emphasis

The most neutral version is the original one: Vstup na swap je zdarma.

That is the safest order for a learner to use.

Because Czech has no articles.

English says:

• The admission to the swap is free
• Admission to the swap is free

Czech simply says:

• Vstup na swap je zdarma.

So when translating from English, do not look for a Czech equivalent of a/an/the. Czech expresses definiteness in other ways, usually through context and word order.