asita tomodati ga watasi no ie ni hon wo tori ni kimasu.

が marks 友達 as the grammatical subject: the friend is the person doing the action.

In this sentence, 友達が simply means the friend is the one who will come.

If you used は instead, the nuance would change. 友達は would sound more like you are making friend the topic, possibly contrasting them with someone else.

• 友達が来ます = A friend / my friend is coming
• 友達は来ます = As for my friend, they are coming

In isolated example sentences like this, が is very common.

の links nouns together. Here it shows possession or association.

• 私 = I / me
• 私の = my
• 家 = house / home

So 私の家 means my house or my home.

This is one of the most basic uses of の:

• 私の本 = my book
• 友達の家 = my friend’s house

Here, に marks the destination of movement.

Since the sentence includes 来ます (to come), 私の家に means to my house.

So:

• 家に来ます = come to the house
• 学校に行きます = go to school

In this sentence, the friend is coming to the speaker’s house, so に is the natural particle.

を marks the direct object of the verb.

The thing being picked up is 本 (book), so 本を means the book as the object of 取りに来ます.

Even though English might phrase the whole idea as come to get a book, Japanese still marks book as the object of 取る (to take / pick up):

• 本を取る = take/pick up a book
• 本を取りに来る = come to pick up a book

This is a very common Japanese pattern:

verb stem + に + motion verb

It means go/come in order to do something.

Here:

• 取ります = to take / pick up
• verb stem = 取り
• 来ます = come

So:

• 取りに来ます = come to pick it up
• more literally: come for the purpose of taking/picking it up

Other examples of the same pattern:

• 食べに行きます = go to eat
• 見に来ます = come to see
• 買いに行きます = go to buy

This is one of the most useful sentence patterns in Japanese.

Because the grammar pattern is specifically:

masu-stem + に + 来る / 行く

So from 取ります, you remove ます and get the stem 取り.

• 取ります → 取り
• 取りに来ます = come to pick up

取りますに来ます is not grammatical Japanese.

As for 取って来ます, that means something different. It usually means go get it and come back or bring it after fetching it. The nuance is not the same as come here in order to pick it up.

So:

• 取りに来ます = come to pick it up
• 取って来ます = go get it and come back / bring it

Japanese chooses come or go based on perspective, much like English.

Because the destination is 私の家 (my house), the movement is toward the speaker’s location, so Japanese uses 来ます (come), not 行きます (go).

Compare:

• 友達が私の家に来ます = My friend is coming to my house
• 友達が店に行きます = My friend is going to the store

So the speaker imagines the friend moving toward the speaker’s side/location.

明日 (tomorrow) is placed at the beginning because time expressions often come early in Japanese sentences. It sets the time frame first.

That said, Japanese word order is more flexible than English, as long as the particles make the roles clear.

This sentence could also be arranged in other ways, such as:

• 友達が明日私の家に本を取りに来ます。

This still means the same thing.

A useful basic pattern is:

Time + subject + place + object + verb

That is exactly what this sentence does.

It could often be omitted if the meaning is already clear from context.

Japanese frequently leaves out information that both speakers understand. So if it is obvious whose house is meant, people may simply say:

• 明日、友達が家に本を取りに来ます。

That would often be understood as Tomorrow, my friend is coming to my house to pick up a book/the book.

Japanese tends to avoid repeating obvious subjects, possessors, and other information.

来ます is the polite -ます form. It is appropriate in neutral polite conversation, with teachers, strangers, coworkers, and in textbook examples.

The casual/plain form is:

• 来る = to come

So the casual version of the full sentence would be:

• 明日、友達が私の家に本を取りに来る。

If you are speaking casually with friends or family, that form is natural. In polite situations, 来ます is better.

A natural reading is:

あした ともだち が わたし の いえ に ほん を とり に きます。

Key readings:

• 明日 = あした
• 友達 = ともだち
• 私 = わたし
• 家 = いえ
• 本 = ほん
• 取りに来ます = とりにきます

Notice that 来ます is read きます, so 取りに来ます becomes とりにきます.

No, normal Japanese writing usually does not use spaces between words.

This sentence would normally be written more like:

明日友達が私の家に本を取りに来ます。

Spaces are often added in beginner materials to help learners see the parts of the sentence more clearly.

So the spaced version is a teaching aid, not standard everyday writing.