deetasiyouryou ga sukunai.

• データ = data
• 使用量 = amount used, usage amount
  
  • 使用 = use / usage
  • 量 = quantity / amount
• が = subject marker
• 少ない = is little / is small in amount / is low

So the structure is basically:

データ使用量 + が + 少ない
= The data usage is low / There is little data usage

A very literal translation would be As for the amount of data used, it is small.

It is read しようりょう.

So the full sentence is:

データ使用量が少ない。
データしようりょうがすくない。

A pitch-accent explanation usually is not necessary at this stage, but it is useful to get comfortable saying it as one chunk:

データ使用量 = データしようりょう

In this sentence, が marks データ使用量 as the thing being described by 少ない.

So:

• データ使用量が少ない = Data usage is low

Using が is very natural when you are simply stating a property of something.

If you used は instead:

• データ使用量は少ない

that would also be grammatical, but it gives more of a topic/comment feeling, like:

• As for data usage, it is low
• possibly with contrast, depending on context

So the difference is roughly:

• が = identifies what is low
• は = sets it up as the topic, sometimes with contrast or emphasis

In isolated statements like this, が is very common.

少ない is an i-adjective, and in Japanese an i-adjective can act as the predicate by itself.

That means you do not need a separate verb like is.

So:

• データ使用量が少ない。 literally works as
• Data usage low. which in natural English becomes
• The data usage is low.

This is normal Japanese grammar.

Compare:

• 高い = is expensive / is high
• 大きい = is big
• 少ない = is few / is little / is low in amount

With i-adjectives, the plain form already ends the sentence naturally.

So:

• 少ない。 = plain form
• 少ないです。 = polite form

You do not say:

• 少ないだ ✘

That is incorrect.

So for this sentence:

• データ使用量が少ない。 = plain, casual/dictionary-style
• データ使用量が少ないです。 = polite

少ない means that the quantity is not much. Depending on the noun, English may translate it differently:

• 人が少ない = there are few people
• お金が少ない = there is little money
• データ使用量が少ない = data usage is low / small

So the core idea is not much in amount.

With 使用量 specifically, natural English usually prefers:

• low
• small
• little

rather than a very literal few.

Yes. データの使用量が少ない is also correct.

The difference is:

• データ使用量 = a compound noun, very compact, common in technical or written contexts
• データの使用量 = more clearly shows the usage amount of data

Both are understandable and natural. In product descriptions, settings, ads, or technical writing, the compact compound データ使用量 is especially common.

Yes, it is natural, especially in contexts like:

• phone plans
• apps
• internet services
• device settings
• product descriptions

It sounds like a concise statement such as:

• This app uses little data
• Data consumption is low

In some contexts, Japanese might also use related expressions such as:

• データ通信量が少ない = data communication volume is low
• 通信量が少ない = data traffic/usage is low

But データ使用量が少ない is perfectly understandable and natural.

Yes. In English, we often translate this kind of Japanese more naturally depending on context.

Literal structure:

• Data usage is low

Natural contextual translation:

• It uses little data
• This app uses little data
• This plan requires little data

Japanese often leaves the subject unstated, so the sentence may be describing something understood from context, such as an app, device, service, or feature.

Japanese often omits information that is obvious from context.

So although the sentence only says:

• データ使用量が少ない。

the fuller idea might be something like:

• このアプリはデータ使用量が少ない。
• このプランはデータ使用量が少ない。
• この機能はデータ使用量が少ない。

In English, we usually need to supply that subject:

• This app uses little data
• This plan has low data usage

So one common challenge for learners is that Japanese often sounds more minimal than English.

Yes. 少ない is commonly used with nouns that represent a quantity or amount.

Examples:

• 人が少ない = there are few people
• 時間が少ない = there is little time
• お金が少ない = there is little money
• データ使用量が少ない = data usage is low

One thing to notice is that 少ない describes the amount/number of something, not usually the physical size of an object.

So:

• 小さい = small in size
• 少ない = small in amount / few / little

That distinction is important.

Polite:

• データ使用量が少ないです。 = Data usage is low.

Negative:

• データ使用量が少なくない。 = Data usage is not low.
• データ使用量が少なくありません。 = polite negative

Past:

• データ使用量が少なかった。 = Data usage was low.
• データ使用量が少なかったです。 = polite past

The stem changes like this because 少ない is an i-adjective:

• 少ない
• 少なくない
• 少なかった
• 少なくなかった

The basic Japanese order is:

noun + が + adjective

So:

• データ使用量 = the thing being talked about
• が = marks it
• 少ない = says what it is like

Japanese predicates come at the end, so this is the normal order.

English says:

• Data usage is low

Japanese says:

• Data usage + subject marker + low

That sentence-final predicate is one of the most important Japanese word-order patterns to get used to.