Какие бы слова ты ни выбрал, главное — говорить спокойно и честно.

This is a very common Russian pattern meaning whatever words you choose or no matter what words you choose.

The structure is:

какие бы ... ни + verb

It expresses concession: the exact choice does not matter. So the sentence is not asking a question, even though какие normally means which / what kind of.

Together, бы and ни form a fixed concessive pattern:

• кто бы ни... = whoever
• что бы ни... = whatever
• где бы ни... = wherever
• какие бы ... ни... = whatever ... / no matter which ...

In this pattern:

• бы adds a hypothetical or open-choice sense
• ни helps give the meaning no matter which / whichever

So Какие бы слова ты ни выбрал means that the specific words do not matter.

Also, this is ни, not не. Here ни is part of the construction, not simple negation.

Russian бы often appears near the beginning of its clause, usually after the first important word.

So:

Какие бы слова ты ни выбрал

is the normal, natural order.

Placing бы later is sometimes possible in other contexts, but in this kind of pattern, putting it right after the question/relative word is the most standard choice.

After бы, Russian typically uses the past-tense form of the verb to create a conditional or non-literal meaning.

So выбрал here does not mean that the action happened in the past. It is simply the form Russian uses in this pattern.

You can think of it roughly as:

• whatever words you choose
• whatever words you may choose
• whatever words you might choose

So the past form here is grammatical, not truly past in meaning.

This is about aspect.

• выбрать = perfective, to choose/select, with focus on the result
• выбирать = imperfective, to be choosing / choose repeatedly / focus on process

Here the speaker means whatever words you end up choosing, so the completed choice matters. That is why выбрал from выбрать is the natural form.

If you used выбирал, it would shift the meaning toward process or repeated choosing, which does not fit as well here.

Слова is accusative plural here, because it is the direct object of выбрал.

The singular noun is:

• слово = word

Plural:

• nominative plural: слова
• accusative plural: слова

Because слово is inanimate, its accusative plural looks the same as the nominative plural.

The adjective/pronoun какие agrees with it in plural as well.

Yes. Ты is the informal singular form of you.

So this sentence sounds personal, direct, and informal.

If you wanted a formal or plural version, you could say:

Какие бы слова вы ни выбрали, главное — говорить спокойно и честно.

Notice that with вы, the verb changes to выбрали, because вы takes plural agreement in the past tense.

Главное is the neuter singular form of главный, used by itself to mean the main thing or what matters most.

In Russian, this is a very common way to introduce the essential point:

• Главное — не спешить.
• Главное — понять идею.

So here:

главное — говорить спокойно и честно

means:

the main thing is to speak calmly and honestly

The comma separates the subordinate clause from the main clause:

• Какие бы слова ты ни выбрал = subordinate concessive clause
• главное — говорить спокойно и честно = main clause

The dash after главное is very common in Russian when one part of the sentence is being identified or explained by the next part.

So:

Главное — говорить спокойно и честно

is like saying:

The main thing is to speak calmly and honestly.

Russian often uses a dash where English would use is.

Говорить is an infinitive, so it expresses a general principle:

the main thing is to speak calmly and honestly

It is not phrased as a direct command.

If you said:

Говори спокойно и честно

that would mean:

Speak calmly and honestly

That is more direct and imperative. The original sentence sounds more reflective and general.

Because they describe how the person should speak.

They modify the verb говорить, so Russian uses adverbs:

• спокойно = calmly
• честно = honestly

If you used adjective forms like спокойный or честный, they would describe a person or noun, not the manner of speaking.

Some parts can move, but the original order is the most natural and clear.

For example, the second half could sometimes be rearranged for emphasis:

• Главное — спокойно и честно говорить
• Главное — говорить честно и спокойно

These are possible, but they sound slightly different in rhythm or emphasis.

The first half, however, is most natural as:

Какие бы слова ты ни выбрал

because that fixed какие бы ... ни pattern is very stable.