אין כניסה בלי כרטיס.

Because אין is the normal way to say that something does not exist / is not available.

In this sentence, אין כניסה means something like there is no entry or entry is not allowed.

By contrast, לא usually negates:

• verbs: לא נכנסים = people do not enter / do not go in
• adjectives or other predicates in many contexts

So on a sign, אין + noun is a very common pattern:

• אין חניה = no parking
• אין מעבר = no passage
• אין כניסה = no entry

Yes, from an English point of view it may feel like a verb is missing, but in Hebrew this is normal.

Hebrew often does not use a separate present-tense verb for is / are in simple sentences. And with אין, the idea of there is not is already built in.

So:

• אין כניסה literally = there is no entry
• not something like entry is not

This is very natural Hebrew, especially on signs.

כניסה is a noun, not a verb. It means entry or entrance.

It comes from the same root as words related to entering, such as:

• להיכנס = to enter / to go in
• נכנס = entered / goes in

So the sign is using a noun-based style that is very common in public notices:

• אין כניסה = no entry rather than
• אסור להיכנס = it is forbidden to enter

Both are possible, but the noun version is especially common on signs.

בלי means without.

So:

• בלי כרטיס = without a ticket

It is a very common preposition in everyday Hebrew. It can be followed by:

• a noun: בלי כרטיס
• an infinitive: בלי לשאול = without asking

In this sentence, it introduces the condition required for entry: no ticket, no entry.

Because Hebrew often uses the singular for a general idea like without a ticket.

So בלי כרטיס does not mean only one specific ticket in a narrow sense. It means without having a ticket in general.

This is similar to English signs that say:

• No entry without ticket even though in normal full English we often say without a ticket.

Using the plural בלי כרטיסים would usually sound less natural here unless the context really involved multiple tickets.

Because Hebrew has no indefinite article. There is no separate word for a / an.

So:

• כרטיס can mean a ticket or just ticket, depending on context
• הכרטיס means the ticket

Here, בלי כרטיס naturally means without a ticket.

This order is short, direct, and very natural for a sign.

It is built like this:

• אין כניסה = no entry
• בלי כרטיס = without a ticket

So the sentence presents the rule first, then the condition.

You could also say:

• בלי כרטיס אין כניסה

That would mean the same thing, but it puts more emphasis on without a ticket. On a sign, אין כניסה בלי כרטיס is the more standard-looking wording.

A natural pronunciation is:

ein kni-SA bli kar-TIS

More closely:

• אין = ein or ayn
• כניסה = kni-SA
• בלי = bli
• כרטיס = kar-TIS

The main stress is on:

• כניסָה
• כרטִיס

Yes. This is very much sign language in the sense of public notice style, not sign language like ASL.

Hebrew signs often prefer short noun-based expressions:

• אין כניסה
• אין עישון
• אין צילום

A fuller spoken sentence might be:

• אסור להיכנס בלי כרטיס = it is forbidden to enter without a ticket
• אי אפשר להיכנס בלי כרטיס = it is impossible to enter without a ticket

But for a sign, אין כניסה בלי כרטיס is concise and completely natural.

Yes, context matters.

In theory, אין כניסה could literally be understood as there is no entrance. But on doors, gates, hallways, and warning signs, it is normally understood as no entry or do not enter.

So the phrase is a fixed sign expression. In real life, people read it as a rule, not as a physical description of the building.