tukue no sita ni kaban ga arimasu.

You’re right: Japanese is normally written without spaces.

So the natural written form is:

机の下にかばんがあります。

The spaces in:

机　の　下　に　かばん　が　あります。

are just there to help beginners see the parts more clearly.

Here, の links two nouns together.

• 机 = desk
• 下 = under / below

So 机の下 literally means the desk’s underside / the area under the desk, or more naturally, under the desk.

In many cases, A の B can mean:

• B of A
• A’s B
• B related to A

So:

• 机の下 = under the desk
• 学校の先生 = the school’s teacher / a teacher at the school

Japanese often expresses location with nouns such as:

• 上 = ऊपर / above / on top
• 下 = under / below
• 中 = inside
• 前 = in front
• 後ろ = behind
• 横 = beside

These location words usually combine with another noun using の:

• 机の下 = under the desk
• いすの前 = in front of the chair
• 箱の中 = inside the box

So unlike English, where under is a preposition, Japanese often builds this idea as [noun] + の + [location noun].

に marks the location where something exists with verbs like:

• あります for things
• います for people/animals

So in this sentence:

• 机の下に = at / in / under the desk
• かばんがあります = there is a bag

Together: There is a bag under the desk.

With existence verbs, に often marks where something is.

Examples:

• 部屋にベッドがあります。 = There is a bed in the room.
• 公園に子どもがいます。 = There are children in the park.

This is a very common question.

In かばんが あります, が marks the thing that exists.

So the sentence is presenting the bag as the item being identified in that location:

• 机の下に かばんが あります。
• Under the desk, there is a bag.

Basic idea

• が often marks the thing being noticed, identified, or newly introduced.
• は often marks the topic, something already being talked about or contrasted.

Compare:

• 机の下にかばんがあります。
  = There is a bag under the desk.
  (introducing the existence of a bag)

• かばんは机の下にあります。
  = The bag is under the desk.
  (talking about the bag as the topic)

Both are possible, but they have slightly different focus.

Both mean to exist / to be, but they are used for different kinds of things.

• あります → for inanimate things
  such as books, bags, desks, cars
• います → for animate beings
  such as people and animals

So:

• かばんがあります。 = There is a bag.
• 猫がいます。 = There is a cat.

Because かばん is an object, あります is correct.

In this kind of sentence, Japanese uses the verb ある (あります in polite form) to mean:

• there is
• to exist
• sometimes to be located

So rather than saying something exactly like English is, Japanese says something closer to:

• A exists at location B

That’s why:

机の下にかばんがあります。

is literally something like:

At under the desk, a bag exists.

Natural English: There is a bag under the desk.

Japanese word order is often different because Japanese usually places the verb at the end.

This sentence is:

• 机の下に = under the desk
• かばんが = bag
• あります = exists / there is

So the structure is roughly:

[place] + [thing] + [exists]

That is very normal in Japanese.

A very common pattern is:

[place] に [thing] が あります / います

meaning:

There is / are [thing] in/at [place].

Yes, in real usage the meaning can overlap with The bag is under the desk, but the nuance is a little different.

• 机の下にかばんがあります。
  focuses on the existence of a bag in that location
  = There is a bag under the desk.

• かばんは机の下にあります。
  focuses on where the bag is
  = The bag is under the desk.

English often uses different sentence patterns, but Japanese may express both ideas with similar structures depending on topic and focus.

Yes, the exact English translation can vary depending on context.

• 下 means below / under
• 机 usually means desk, but in some contexts learners may compare it with table

So 机の下に could be translated as:

• under the desk
• beneath the desk
• below the desk

The Japanese meaning stays the same; the English wording may change slightly.

They are similar, but not always identical in nuance.

• かばん is a very common native/Japanese-style word for bag
• バッグ is a loanword from English bag

In many everyday situations they overlap a lot. But depending on context:

• かばん can sound more general or traditional
• バッグ can sometimes sound more like a fashion bag, handbag, or modern item

For this sentence, かばん is completely natural.

あります is the polite form of ある.

• plain form: ある
• polite form: あります

Textbooks often use the polite form first because it is safer and more generally useful in conversation.

So:

• 机の下にかばんがある。 = plain/casual
• 机の下にかばんがあります。 = polite

Both mean the same thing, but the level of politeness is different.

You would make あります negative:

• あります → ありません

So:

机の下にかばんがありません。
= There is no bag under the desk.

In plain form:

机の下にかばんがない。

Normally, no.

With ある / いる, the location where something exists is marked by に, not で.

• に = location of existence
• で = location where an action happens

So:

• 机の下にかばんがあります。 = There is a bag under the desk.
  ✅ correct

But 机の下でかばんがあります is not correct for simple existence.

Compare with an action:

• 机の下で猫が寝ています。 = A cat is sleeping under the desk.
  Here で is used because sleeping is treated as an action/state happening there.

Japanese nouns do not usually show a/an/the the way English does.

So かばん by itself can mean:

• a bag
• the bag
• bags

depending on context.

In this sentence, because the bag is being introduced as something that exists there, a bag is usually the most natural translation:

There is a bag under the desk.

But in a different context, it could be understood as the bag if both speakers already know which bag is meant.

A very useful pattern is:

[place] に [thing] が あります / います

Meaning:

There is / are [thing] in/at [place].

For inanimate things:

• 部屋にテレビがあります。 = There is a TV in the room.

For people/animals:

• 教室に先生がいます。 = There is a teacher in the classroom.

Your sentence fits this exactly:

• 机の下に = under the desk
• かばんが = a bag
• あります = there is

So the whole sentence means:

There is a bag under the desk.