Mi eniris la vendejon, ĉar mi vidis grandan rabaton ĉe la pordo.

Both can work, but they are built differently.

• eniri = to enter / to go in
• iri en = to go into

So:

• Mi eniris la vendejon = I entered the shop.
• Mi iris en la vendejon = I went into the shop.

With eniri, the verb itself already contains the idea of into, so it often takes a direct object: la vendejon.

This is very common in Esperanto. Many verbs with prefixes work this way:

• eliri = go out
• reveni = come back
• foriri = go away

Because it is the direct object of eniris.

In this sentence, eniri is being used as a transitive verb, so the place entered is marked with the accusative:

• la vendejo = the shop
• la vendejon = the shop, as the direct object

So Mi eniris la vendejon literally works like I entered the shop.

This is different from a sentence like:

• Mi iris en la vendejon

There, the -n on vendejon is not because it is a direct object. It is because en plus -n can show motion into something.

So the same ending can appear for different reasons, but here the simplest explanation is: it is the object of eniris.

Vendejo is built from parts:

• vend- = sell
• -ej- = place
• -o = noun ending

So vendejo literally means a place for selling.

That is why it means shop, store, or storefront/business premises, depending on context.

The suffix -ej- is very useful in Esperanto. For example:

• lernejo = school, a place for learning
• kuirejo = kitchen, a place for cooking
• dormejo = dormitory / sleeping place

La is the definite article, meaning the.

Here, la vendejon means the shop rather than a shop. In context, it usually suggests a specific shop the speaker is talking about.

Esperanto uses la somewhat like English the, though exact usage can depend on context. If you said:

• Mi eniris vendejon

that would sound more like I entered a shop.

So la helps make the shop definite or identifiable.

Because ĉar introduces a subordinate clause meaning because.

Esperanto often uses commas to separate clauses, especially when a conjunction like ĉar introduces an explanation or reason.

So the structure is:

• Mi eniris la vendejon = main clause
• ĉar mi vidis grandan rabaton ĉe la pordo = subordinate clause giving the reason

The comma helps show that division clearly.

Because the second clause needs its own subject.

In English, we also say:

• I entered the shop because I saw...

We do not normally say:

• I entered the shop because saw...

Esperanto works the same way here. After ĉar, you start a new clause, and that clause needs a subject:

• ĉar mi vidis...

Even though it is the same person, mi must still be stated.

Because adjectives agree with the nouns they describe.

Here:

• rabato = discount
• rabaton = discount, as accusative/direct object
• granda = big
• grandan = big, matching an accusative noun

So:

• grandan rabaton = a big discount, as the object of vidis

In Esperanto, adjectives match nouns in:

• number
• accusative marking

So if the noun has -n, the adjective also has -n.

Examples:

• granda rabato = a big discount
• grandan rabaton = a big discount as object
• grandaj rabatoj = big discounts
• grandajn rabatojn = big discounts as objects

Rabato means discount or price reduction.

So granda rabato is a big discount.

In context, English might translate it as:

• a big discount
• a great sale
• a large markdown

But the core meaning is specifically discount, not necessarily the entire event of a sale.

So if the speaker saw a sign showing lower prices, rabato is a very natural word.

Ĉe means at, by, with, or near, depending on context.

Here, ĉe la pordo means something like:

• at the door
• by the door
• near the door

It suggests the discount sign or notice was located around the entrance area.

This is different from:

• sur la pordo = on the door
• en la pordo = in the door / in the doorway
• apud la pordo = beside the door

So ĉe is a broad, natural choice when you mean the general location near the door.

Vidi literally means to see, but like English see, it can also mean notice or spot.

So in this sentence, mi vidis grandan rabaton can mean:

• I saw a big discount
• I noticed a big discount
• I spotted a big discount sign

This is very normal. It does not have to mean only the physical act of seeing; it can also imply becoming aware of something visually.

Yes. That is perfectly natural Esperanto.

Both orders are fine:

• Mi eniris la vendejon, ĉar mi vidis grandan rabaton ĉe la pordo.
• Ĉar mi vidis grandan rabaton ĉe la pordo, mi eniris la vendejon.

The meaning stays basically the same. The difference is mainly emphasis:

• first version: starts with the action
• second version: starts with the reason

Esperanto word order is fairly flexible, but the normal neutral order is still usually straightforward and easy to follow.

The letter ĉ is pronounced like ch in church.

So:

• ĉar sounds roughly like char
• ĉe sounds roughly like cheh

These are separate letters in Esperanto, not just decorated versions of c.

A useful contrast:

• c = like ts in cats
• ĉ = like ch in church

So ĉar and ĉe should both begin with a ch sound.