raigetu no ensoku ha yama ni iku yotei desu.

In normal Japanese writing, this sentence would usually be written without spaces:

来月の遠足は山に行く予定です。

The spaces here are just for learners, to make the parts easier to see. Japanese does not normally separate words the way English does.

の connects nouns. In this sentence, it links 来月 and 遠足:

• 来月 = next month
• 遠足 = excursion / school trip / outing
• 来月の遠足 = the excursion next month or next month’s excursion

So の often works a bit like English ’s or of, depending on the phrase.

は marks the topic of the sentence.

So 来月の遠足は means something like:

• As for next month’s excursion...
• Regarding next month’s excursion...

The sentence is then telling you something about that topic: it is scheduled to go to the mountain.

A common beginner mistake is to think は always means is. It does not. It marks what the sentence is talking about.

With movement verbs like 行く (to go), に often marks the destination.

So:

• 山に行く = go to the mountain / go to the mountains

Here, に answers where to?

You could also sometimes use へ with 行く:

• 山へ行く

That also means go to the mountain, but に is very common and slightly more direct as a destination marker.

Because when a verb comes before 予定, it normally uses the plain form, not the -ます form.

So the pattern is:

• dictionary/plain verb + 予定です

Examples:

• 行く予定です = plan to go / be scheduled to go
• 食べる予定です = plan to eat / be scheduled to eat
• 帰る予定です = plan to return / be scheduled to return

So 行きます予定です is not correct Japanese.

予定 means schedule, plan, or arrangement.

So 山に行く予定です literally means something like:

• It is a plan to go to the mountain
• It is scheduled to go to the mountain

In natural English, that becomes:

• The excursion is planned to go to the mountain
• The excursion will go to the mountain
• The plan is to go to the mountain

This expression is often used for things that are scheduled, arranged, or expected.

In Japanese, verbs in plain form can modify nouns directly.

So:

• 行く予定 = the plan to go
• literally, go-plan

This is very different from English word order, but it is a normal Japanese pattern.

You can think of it like this:

• [verb] + 予定
• [to do something] + plan

So 山に行く予定です is built from:

• 山に行く = go to the mountain
• 予定 = plan/schedule
• です = polite ending

Japanese often leaves out the subject when it is obvious from context.

In this sentence, the topic is 来月の遠足 (next month’s excursion), so the idea is that the excursion involves going to the mountain. In natural English, you might say:

• Next month’s excursion is scheduled to go to the mountain
• We’re going to the mountain for next month’s excursion

The exact English subject depends on context, but in Japanese it does not need to be stated if listeners can already infer it.

Sometimes, but the nuance changes.

• 予定です = scheduled / planned / arranged
• つもりです = intend to do

So:

• 山に行く予定です sounds like there is a plan or schedule.
• 山に行くつもりです sounds more like someone’s personal intention.

For a school excursion, 予定です fits better because it sounds like an organized plan, not just someone’s personal decision.

Japanese usually does not mark articles (a, an, the) the way English does, and it often does not mark singular vs. plural unless it matters.

So 山 could be understood in English as:

• the mountain
• a mountain
• sometimes even the mountains

The correct English version depends on context. Japanese leaves that kind of detail unstated unless it is important.