raigetu kekkonsimasu.

It is read:

• 来月 → らいげつ (raigetsu)
• 結婚します → けっこんします (kekkon shimasu)

So the whole sentence is:

らいげつ　けっこんします。

A natural pronunciation will make けっこん sound like a doubled consonant in the middle: kek-kon.

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

So instead of saying something like:

• 私は来月結婚します。

people very often just say:

• 来月結婚します。

If the conversation already makes it obvious who is speaking, the subject is unnecessary. This is extremely common in Japanese.

来月 is a time expression meaning next month, and with this kind of relative time word, Japanese often uses it without a particle.

So:

• 来月結婚します。 is natural.

Words like these often do not need に:

• 今日 = today
• 明日 = tomorrow
• 来週 = next week
• 来月 = next month
• 去年 = last year

By contrast, more specific time points often take に, such as:

• 3月に
• 7時に
• 月曜日に

So this sentence sounds natural without any particle after 来月.

Usually, 来月結婚します is the more natural choice.

With relative time words like 来月, に is generally omitted. Adding に may sound unnatural or overly marked in many normal situations.

So for a learner, the safest pattern is:

• 来月結婚します。
• not usually 来月に結婚します。

します is the polite form of する.

• 結婚する = plain form
• 結婚します = polite form

Japanese often uses the polite form in everyday conversation, especially with people you do not know well, in formal situations, or when speaking politely in general.

So this sentence is a polite statement.

It is built from:

• 結婚 = marriage / getting married
• する = to do

Together, 結婚する acts as a verb meaning to marry / to get married.

This is a very common Japanese pattern called a suru-verb:

• 勉強する = to study
• 運動する = to exercise
• 結婚する = to marry / get married

So grammatically, 結婚します is a noun + する, but it functions like a normal verb.

Usually, in a sentence like this, it means to get married.

Japanese often does not force the same distinction English does.

If you want to mention the person, you can use と:

• 来月、田中さんと結婚します。
  = I’m getting married to Tanaka next month.

Without と, the sentence simply says that the speaker is getting married.

Japanese often puts time expressions near the beginning of the sentence.

So this order is very common:

• 来月結婚します。

It helps set the time frame first, then gives the action.

Japanese word order is more flexible than English, but putting the time expression first is extremely natural.

Yes. In Japanese, the non-past form covers both present and future, depending on context.

Here, because 来月 means next month, the sentence clearly refers to the future.

So 結婚します here means something like:

• will get married
• am getting married

The time word makes the future meaning clear.

Yes, that is very natural.

In writing, Japanese often uses a comma after a time expression:

• 来月、結婚します。

The comma shows a small pause and makes the sentence easier to read. In speech, there is often a slight pause after 来月 as well.

Without the comma, the sentence is still correct:

• 来月結婚します。

Both are natural.

It is a complete and natural sentence.

Even though English often wants more information, Japanese does not always need to state:

• the subject
• the partner
• the exact date
• the reason

If the context is already known, 来月結婚します。 is perfectly normal and complete.

It sounds like a simple announcement of a personal plan or life event.