Если у тебя есть другая идея, не бойся возражать, но говори спокойно.

Russian usually expresses possession with the pattern у + genitive + есть.

So:

• у тебя = at you / with you
• есть = there is / there exists

Together, у тебя есть другая идея literally means something like there is another idea with you, which is the normal Russian way to say you have another idea.

A verb like иметь does exist, but it is much less common in everyday speech for simple possession. Saying ты имеешь другую идею would sound unnatural here.

Because идея is a feminine noun, and the adjective must agree with it in gender, number, and case.

• идея = feminine, singular, nominative
• so другой changes to другая

Compare:

• другой план = another plan (masculine)
• другая идея = another idea (feminine)
• другое мнение = another opinion (neuter)

It is in the genitive case.

The structure у кого есть что requires:

• у
  • genitive for the possessor
• the thing possessed in the nominative

So:

• у меня есть
• у тебя есть
• у него есть
• у нас есть

That is why you see тебя, not ты.

In this sentence, есть is normally used because it introduces the existence of something: you have another idea.

• У тебя есть другая идея = You have another idea

In some contexts, есть can be dropped, especially when the meaning is more about possession in a general sense or in informal speech:

• У меня брат = I have a brother
• У меня есть брат = also possible, often a bit more emphatic or explicit

Here, есть sounds natural and standard.

Бойся is the imperative form of the verb бояться (to be afraid).

• бояться = to be afraid
• бойся = be afraid
• не бойся = don’t be afraid

So не бойся возражать means don’t be afraid to object / to disagree.

This is a very common pattern in Russian:

• не бойся спрашивать = don’t be afraid to ask
• не бойся говорить = don’t be afraid to speak
• не бойся ошибаться = don’t be afraid to make mistakes

Many Russian verbs end in -ся, and бояться is simply the normal dictionary form for to be afraid. It is not something you usually analyze as a literal reflexive in modern usage.

So you just learn it as a whole verb:

• я боюсь
• ты боишься
• не бойся

English learners sometimes expect a non-reflexive verb here, but Russian does not use one.

This is about aspect.

• возражать = imperfective
• возразить = perfective

After не бойся, the imperfective often sounds more natural because it refers to the action in a general, ongoing, or repeated sense:

• не бойся возражать = don’t be afraid to speak up / object when necessary

If you said не бойся возразить, it would sound more like don’t be afraid to make one objection / to respond once.

In this sentence, the speaker is giving general advice, so возражать fits better.

Возражать means to object, to disagree, or to speak against something.

Its strength depends on context. It does not necessarily mean an angry argument. In this sentence, especially because of но говори спокойно, it suggests:

• it is okay to disagree
• it is okay to speak up
• but do it calmly

So here возражать is closer to to voice disagreement than to to fight.

Again, this is an aspect choice.

• говорить = imperfective
• сказать = perfective

Говори спокойно means speak calmly or talk calmly. It focuses on the manner of speaking, not on one completed utterance.

If you said скажи спокойно, it would sound more like say it calmly or say it in a calm way, referring more to a specific thing to be said.

Here the advice is general, so говори спокойно is the natural choice.

Спокойно is an adverb, formed from the adjective спокойный (calm).

• спокойный голос = a calm voice
• говорить спокойно = to speak calmly

So it describes how the person should speak.

Russian punctuation is quite strict here.

1. Если у тебя есть другая идея, ...
   A comma separates the если clause (if...) from the main clause.

2. ..., не бойся возражать, но говори спокойно.
   A comma is placed before но (but) because it joins two clauses/commands:

   • не бойся возражать
   • говори спокойно

So the commas are required by standard Russian punctuation.

Yes, it is informal singular because it uses:

• у тебя
• не бойся
• говори

For formal singular or plural, you would use вы forms:

• Если у вас есть другая идея, не бойтесь возражать, но говорите спокойно.

Changes:

• тебя → вас
• бойся → бойтесь
• говори → говорите

Yes. Russian word order is flexible, though the original version is very natural.

Original:

• Если у тебя есть другая идея, не бойся возражать, но говори спокойно.

You could also hear:

• Если у тебя есть другая идея, возражать не бойся, но говори спокойно.

That said, the original order is clearer and more neutral.

Russian often changes word order for emphasis, but not every rearrangement sounds equally natural. For a learner, the original sentence is a good model to follow.