На сцене нужно держаться уверенно и говорить чуть медленнее.

На сцене means on the stage or when on stage, and сцене is in the prepositional case.

Why?

• The preposition на can mean on or at.
• When it answers where?, it usually takes the prepositional case.
• сцена → на сцене

Compare:

• на сцене = on the stage / while on stage
• на сцену = onto the stage (motion toward, accusative case)

So in this sentence, it is talking about being located there, not moving there.

Нужно means something like it is necessary, one should, or you need to.

In this sentence, it is used impersonally:

• нужно держаться... и говорить... = it is necessary to behave... and to speak...

Russian often leaves out the subject in this kind of statement. English usually wants a subject such as you, but Russian does not need one here.

This makes the sentence sound general:

• When on stage, you need to carry yourself confidently and speak a little more slowly.

Because after impersonal words like нужно, Russian commonly uses the infinitive.

Pattern:

• нужно + infinitive

Examples:

• Нужно работать. = It is necessary to work.
• Нужно подождать. = You need to wait.
• На сцене нужно держаться уверенно. = On stage, you need to carry yourself confidently.

So держаться and говорить are both actions that are required.

Yes, historically it is related to держать (to hold), but in this sentence держаться is an idiomatic verb meaning something like:

• to carry oneself
• to behave
• to present oneself
• to keep one’s composure

So держаться уверенно means:

• to carry yourself confidently
• to appear confident
• to behave in a confident way

It does not mean physically grabbing yourself.

The -ся ending makes the verb reflexive.

Here, держаться is not just держать + oneself in a literal word-for-word sense. It is a normal dictionary verb with its own meaning: to behave / to carry oneself / to keep oneself.

This is common in Russian. Some verbs with -ся develop meanings that are not fully predictable from the non-reflexive version.

Compare:

• держать = to hold
• держаться = to hold oneself / to behave / to keep going / to stay

So you should learn держаться here as a whole expression:

• держаться уверенно

Because the sentence needs an adverb, not an adjective.

• уверенный = confident (adjective, used with a noun)
• уверенно = confidently (adverb, describes how someone behaves or speaks)

Here it describes how a person should carry themselves:

• держаться как? → уверенно

Compare:

• уверенный человек = a confident person
• говорить уверенно = to speak confidently
• держаться уверенно = to carry oneself confidently

Чуть медленнее means a little more slowly or slightly slower.

Breakdown:

• чуть = a little, slightly
• медленнее = more slowly / slower

So:

• говорить чуть медленнее = to speak a little more slowly

This is a very common way to soften advice in Russian. It sounds less harsh than a stronger command.

Because the speaker is not saying speak slowly in an absolute sense. They are saying speak more slowly than you are speaking now, or than usual.

That is why Russian uses the comparative:

• медленно = slowly
• медленнее = more slowly

So:

• говорить медленно = to speak slowly
• говорить медленнее = to speak more slowly

English often uses more slowly, while Russian often uses the single comparative form медленнее.

It is functioning as an adverb here because it describes the verb говорить.

Question:

• говорить как? → медленнее

Russian comparative forms like быстрее, медленнее, лучше are often used this way and may look the same whether you think of them as coming from adjectives or adverbs. In practical terms, here you should understand it as:

• медленнее = more slowly

It applies to both verbs:

• нужно держаться уверенно
• и (нужно) говорить чуть медленнее

Russian often avoids repeating a word when it is clearly understood. So the second нужно is omitted.

In full, the structure is basically:

• На сцене нужно держаться уверенно и нужно говорить чуть медленнее.

But that sounds repetitive, so Russian normally says it only once.

Putting На сцене first sets the context immediately: as for being on stage or when on stage.

Russian word order is flexible, so this sentence could be rearranged, for example:

• Нужно на сцене держаться уверенно и говорить чуть медленнее.

But the original order is natural because it emphasizes the situation first:

• On stage, this is how you should act.

This is very common in Russian: place the setting or context early in the sentence.

Yes. Надо would be very natural too:

• На сцене надо держаться уверенно и говорить чуть медленнее.

Both надо and нужно can mean need to / should / it is necessary to.

Very roughly:

• надо often sounds a bit more conversational
• нужно can sound slightly more neutral or formal

In many everyday contexts, they are interchangeable.

The stresses are:

• на сцене́
• ну́жно
• держа́ться
• уве́ренно
• и говори́ть
• чуть
• ме́дленнее

This is useful because Russian stress is unpredictable and can affect pronunciation a lot.

A learner-friendly reading would be:

• На сцене́ ну́жно держа́ться уве́ренно и говори́ть чуть ме́дленнее.