minna no mae de nihongo de zikosyoukaisuruno ha sukosi kintyousimasu.

They do two different jobs:

• みんなの前で = in front of everyone
  Here, で marks the place/setting where the action happens.

• 日本語で = in Japanese
  Here, で marks the means/method, and with languages it often means using that language.

So even though both are で, they are not redundant. Japanese uses で for several related functions.

前 means front or before, and みんな means everyone.

So:

• みんなの前 = everyone’s front → more naturally, in front of everyone
• の connects the noun みんな to the noun 前

This is a very common pattern:

• 学校の前 = in front of the school
• 駅の前 = in front of the station

Then adding で gives the setting of the action:

• みんなの前で = in front of everyone

Because 日本語 here is not the direct object. It is the language used to do the introduction.

• 日本語で = in Japanese / using Japanese

The particle を would mark a direct object, but Japanese language is not the thing being introduced. The thing happening is self-introducing, and it is being done in Japanese.

Compare:

• 日本語で話す = speak in Japanese
• ペンで書く = write with a pen

In both cases, で marks the means or method.

Both are possible.

• 自己紹介する
• 自己紹介をする

Both mean to introduce oneself.

With many Sino-Japanese nouns that can function like verbal nouns, Japanese often drops を in everyday speech and writing:

• 勉強する = study
• 運動する = exercise
• 自己紹介する = introduce oneself

So 自己紹介する is very natural and common.

The の turns the verb phrase before it into a noun-like idea.

So:

• 自己紹介する = to introduce oneself
• 自己紹介するの = introducing oneself / the act of introducing oneself

Then は marks that whole action as the topic:

• 自己紹介するのは = as for introducing oneself...

In this sentence, the full idea is:

• みんなの前で日本語で自己紹介するのは = introducing myself in Japanese in front of everyone is...

This use of の is called nominalization.

Because the speaker is making the whole action into the topic of the sentence.

The structure is:

• [verb phrase] の は ...

So here:

• みんなの前で日本語で自己紹介するの = the act of introducing oneself in Japanese in front of everyone
• は = marks that as the topic
• 少し緊張します = is a little nerve-racking / makes me a little nervous

It is similar to saying:

• As for introducing myself in Japanese in front of everyone, it makes me a little nervous.

緊張する literally means to become tense or to be nervous.

So:

• 少し緊張します = I get a little nervous / it makes me a little nervous

Even though 緊張 is a noun, 緊張する works like a verb meaning to be nervous.

This is very common in Japanese:

• 心配する = worry
• 勉強する = study
• 緊張する = get nervous

Because 緊張 is not used like a normal adjective here. The natural expression is the verb:

• 緊張する = to get nervous / to feel tense

So:

• 少し緊張します = I get a little nervous

You would not normally say 緊張です for this meaning.

If you wanted an adjective-like wording, Japanese more naturally uses expressions such as:

• 緊張しています = I am nervous
• 緊張気味です = I’m a bit nervous

But in this sentence, 緊張します is perfectly natural.

少し is an adverb meaning a little.

It modifies the verb phrase:

• 少し緊張します = get a little nervous

By contrast, 少ない is an adjective meaning few / not many / not much, and it would not fit naturally here.

So:

• 少し = a little, slightly
• 少ない = few, scarce

It can sound like either, depending on context, but most naturally it expresses a general personal feeling:

• Introducing myself in Japanese in front of everyone makes me a little nervous.

It could also be used right before doing it, like:

• I’m a little nervous about introducing myself in Japanese in front of everyone.

Japanese often leaves that kind of distinction to context.

Because Japanese very often omits subjects when they are clear from context.

In English, you usually need I:

• I get a little nervous...

In Japanese, if the speaker is obviously talking about themself, 私 is usually unnecessary.

So this sentence naturally implies:

• I get a little nervous introducing myself in Japanese in front of everyone.

Adding 私 is possible, but often sounds less natural unless you need emphasis or contrast.

The sentence follows a very common Japanese pattern: put descriptive information before the main predicate.

Breakdown:

• みんなの前で = in front of everyone
• 日本語で = in Japanese
• 自己紹介する = introduce oneself
• のは = the act of ... is / as for ...
• 少し緊張します = is a little nerve-racking / makes me a little nervous

So the structure is basically:

• [where] [in what language] [what action] のは [comment]

Japanese often builds up the situation first, then gives the main comment at the end.

Yes, こと is possible:

• みんなの前で日本語で自己紹介することは少し緊張します。

However, in this kind of sentence, の often sounds more natural and direct when talking about an action as an experience or feeling.

Very roughly:

• の can feel a bit more immediate or concrete
• こと can feel a bit more formal or abstract

Both are grammatical, but するのは is very natural here.

It can be translated a few ways depending on what sounds most natural in English:

• I get a little nervous introducing myself in Japanese in front of everyone.
• Introducing myself in Japanese in front of everyone makes me a little nervous.
• It’s a little nerve-racking to introduce myself in Japanese in front of everyone.

All of these capture the feeling well. Japanese does not always match English sentence structure directly, so a natural translation may sound different from the literal grammar.