ekimae no panya no korokkepan ha ninki ga aru node, hiru ni ha urikirerukoto ga arimasu.

Both の link nouns together.

• 駅前のパン屋 = the bakery in front of the station / the bakery by the station
• パン屋のコロッケパン = the bakery’s croquette bread / the croquette bread from that bakery

So the whole phrase means something like:

• the croquette bread from the bakery in front of the station

Japanese often stacks noun modifiers like this, with the main noun coming at the end. Here, the main noun is コロッケパン.

駅前 literally means in front of the station or more naturally the area around the station.

It is a common compound noun:

• 駅 = station
• 前 = front / before

So 駅前のパン屋 is not necessarily a bakery physically right at the station entrance. It usually means a bakery near the station / in the station-front area.

は marks the topic of the sentence.

So in:

• 駅前のパン屋のコロッケパンは...

the sentence is talking about the croquette bread from the bakery by the station.

A natural way to understand it is:

• As for the croquette bread from the bakery by the station, ...

Everything after that gives information about that topic: it is popular, and because of that, it sometimes sells out by noon.

人気がある is a very common expression meaning to be popular.

• 人気 = popularity
• がある = exists / there is

So literally it is something like popularity exists.

This is just the normal Japanese pattern. Even though 人気 is a noun, 人気がある functions like is popular in English.

You may also see:

• 人気です = it is popular

That is also possible in many situations, but 人気がある is extremely standard and often feels a little more descriptive in sentences like this.

In 人気がある, the が marks the thing that exists: popularity.

This may feel unusual to an English speaker, because English says X is popular, but Japanese often uses a noun + がある pattern:

• 時間がある = have time
• 興味がある = be interested
• 人気がある = be popular

So が is not marking the bread directly. The bread is already the topic with は. Inside the predicate, 人気 is what exists, so it takes が.

Both ので and から can mean because, but ので usually sounds a bit softer, more explanatory, and a little less direct.

Here:

• 人気があるので、昼には売り切れることがあります。
• Because it is popular, it sometimes sells out by noon.

Using ので makes the sentence sound like a calm explanation of the situation.

If you used から instead, it would still be grammatical, but it can sound a bit more direct or subjective depending on context.

昼には is 昼に + は.

• 昼に = at noon / in the daytime / around lunchtime, depending on context
• は adds contrast or emphasis

So 昼には売り切れることがあります suggests something like:

• it can be sold out by noon
• it may already be sold out when noon comes
• at least by lunchtime, it may be gone

The は gives a slight contrastive feeling, as if saying:

• by noon, at least, it may be sold out
• when it gets to noon, it can be sold out

This is a very common use of には.

It could in some contexts, but in this sentence it more naturally means by noon or around lunchtime.

Why? Because the sentence is about something being popular and becoming unavailable:

• 売り切れる = sell out

So the idea is not just that it sells out sometime during the day, but that it may already be sold out by around noon/lunch. Context makes that interpretation the most natural one.

売り切れる means to sell out or to be sold out.

It describes the state/result that all of the item has been sold.

Examples:

• パンが売り切れた。 = The bread sold out.
• チケットはもう売り切れています。 = The tickets are already sold out.

In this sentence, the croquette bread is the thing that sells out.

売り切れることがあります means there are times when it sells out or more naturally it sometimes sells out.

This pattern is very useful:

• dictionary form + ことがある = sometimes happens / there are occasions when ...

So:

• 売り切れることがあります = it sometimes sells out = there are times when it sells out

If the sentence said 売り切れます, it would sound more like a regular/firmer statement:

• it sells out

But ことがあります makes it less absolute and shows that it happens only on some occasions.

In this pattern, こと nominalizes the verb phrase, meaning it turns it into something like the event of selling out.

So:

• 売り切れる = to sell out
• 売り切れること = the fact/event of selling out
• 売り切れることがあります = there are times when that happens

You do not need to translate こと literally every time. It is best to learn verb + ことがある as a set pattern meaning:

• sometimes do
• there are times when ... happens

It is intransitive here.

That means the item itself is described as selling out:

• コロッケパンが売り切れる = the croquette bread sells out

A related transitive verb is 売り切る, which means to sell all of something out / to completely sell.

For example:

• 店がパンを売り切った。 = The store sold out all the bread.

But in your sentence, the focus is on the bread becoming unavailable, so 売り切れる is the natural choice.

Because Japanese puts modifiers before the noun they modify.

English often says:

• The croquette bread from the bakery by the station

Japanese builds that whole noun phrase first:

• 駅前の → modifies パン屋
• 駅前のパン屋の → modifies コロッケパン
• then コロッケパンは marks that whole thing as the topic

So this structure is very normal in Japanese. The important habit is to wait for the final noun:

• 駅前のパン屋のコロッケパン → the main noun is コロッケパン

Yes. パン屋 literally is something like bread shop, but in natural English it is usually bakery.

• パン = bread
• 屋 = shop / store / person associated with a trade

So パン屋 is the normal everyday word for bakery or bread shop.

Yes. That is exactly what 売り切れることがあります suggests.

It means:

• it happens sometimes
• but not every single day or in every case

So the nuance is:

• Because it is popular, it may be sold out by noon rather than
• Because it is popular, it is always sold out by noon