Learn Hardcore Russian: Мой брат смело говорит по-русски перед публикой. - My brother speaks Russian bravely in front of an audience.

говорить по-русски – to speak Russian (literally: to speak in a Russian way), or
говорить на русском (языке) – to speak in Russian (language).

You do not say говорить русский for “speak Russian”.
говорить русский would sound like “to speak a Russian [man]” or “to speak the Russian (thing)”, which is ungrammatical and confusing.

So the natural patterns are:

говорить по-английски / по-немецки / по-французски
говорить на английском / на немецком / на французском (языке)

Why is there a hyphen in по-русски?

по-русски is an adverb formed from the adjective русский with the prefix по- and the suffix -ски.

Russian spelling rule:
Adverbs formed like по- + adjective stem + -ски / -цки / -чески are normally written with a hyphen:

по-русски – in Russian
по-английски – in English
по-немецки – in German
по-человечески – in a human way

So the hyphen is just a standard orthographic rule for this type of adverb.

What is the difference between смелый and смело here?

смелый – adjective: brave, bold (describes a person or a noun)
- смелый брат – a brave brother
- смелое выступление – a bold performance
смело – adverb: bravely, boldly (describes how the action is done)
- Он смело говорит – He speaks bravely
- Она смело отвечает – She answers boldly

In Мой брат смело говорит по-русски перед публикой, we are describing how he speaks, so we need the adverb смело, not the adjective смелый.

Can I move смело to another place in the sentence?

Yes. Russian word order is flexible, and adverbs like смело can move, though the neutral position is before the verb:

Мой брат смело говорит по-русски перед публикой. (neutral, standard)
Мой брат говорит смело по-русски перед публикой. (slight emphasis on говорит смело as a unit)
Мой брат говорит по-русски смело перед публикой. (unusual, with focus shifting to смело)

You can also move other parts for emphasis:

Перед публикой мой брат смело говорит по-русски. – emphasis on “in front of the audience”
По-русски мой брат смело говорит перед публикой. – emphasis on “in Russian”

All are grammatically possible; the differences are mostly about rhythm and what you want to stress.

What exactly does the verb form говорит express here? Is it “speaks” or “is speaking”?

говорит is 3rd person singular, present tense, imperfective of говорить.

It can translate into English as either:

“speaks” (habitual, general ability)
- My brother speaks Russian boldly in front of audiences (in general).
“is speaking” (an action happening now, if context makes that clear)
- My brother is (right now) speaking Russian boldly in front of the audience.

Russian doesn’t have a separate “continuous” tense like English.
Context decides whether говорит is understood as general/habitual or as happening now.

Why is it мой брат and not моя брат or моё брат?

The possessive мой / моя / моё / мои agrees with the gender and number of the noun:

masculine singular: мой брат – my brother
feminine singular: моя сестра – my sister
neuter singular: моё письмо – my letter
plural (any gender): мои братья – my brothers; мои друзья – my friends

брат is masculine singular, so you must use мой:

Мой брат смело говорит по-русски перед публикой.

Could I drop мой and just say Брат смело говорит по-русски перед публикой?

Grammatically, yes, but the meaning changes.

Мой брат… – clearly my brother; this is normal if you’re introducing your brother in conversation.
Брат… without a possessive can sound:
- like talking about “(the) brother” in a very specific known context (e.g., in some families or small communities), or
- stylistically a bit unusual or incomplete, unless context strongly identifies which brother.

Most of the time, when you mean “my brother” in a neutral context, you say мой брат.

Could I use он instead of мой брат and say Он смело говорит по-русски перед публикой?

Yes.

Мой брат смело говорит… – emphasizes that this person is my brother.
Он смело говорит… – “He speaks bravely…”, used when the person is already known from context.

Russian often drops subject pronouns more than English does, but here some explicit subject (either мой брат or он) is necessary, unless the subject is understood from prior context and omitted entirely:

Смотри, как смело говорит по-русски перед публикой!
(Look how bravely [he] speaks Russian in front of the audience!) – subject “he” is understood.

Why is it перед публикой and not something like перед публику?

The preposition перед (“in front of, before”) takes the instrumental case in Russian.

перед кем? чем? – before / in front of whom? what?

публика (nominative singular) → публикой (instrumental singular)

So the correct form is:

перед публикой – in front of the audience / public

Using перед публику would be wrong, because перед never governs the accusative in this sense; it always requires the instrumental.

What is the nuance of перед публикой? Does it mean “in public”?

Not exactly. There is a subtle difference:

перед публикой – literally “in front of the public/audience”;
implies a group of people who are listening/watching, like at a performance, speech, or event.
на публике – “in public”, more like “when people are around / not in private”.
Example: Он стесняется говорить на публике. – He is shy about speaking in public.

In your sentence:

Мой брат смело говорит по-русски перед публикой.
suggests your brother bravely speaks Russian in front of an audience – for example, during a presentation, show, or speech.

Is публика the same as English “public”?

They overlap, but публика in Russian more often means “audience”:

people attending a concert, lecture, performance, etc.
- театральная публика – theatre audience
- выступать перед публикой – to perform / speak before an audience

English “the public” as a broad, abstract group (“the general public”) would more likely be translated as общественность, народ, or just understood from context, not always публика.

So in your sentence, перед публикой is best understood as “in front of an audience”.

Could I say на публике instead of перед публикой here?

You could, but the nuance changes slightly:

перед публикой – emphasizes being in front of an audience (stage-like situation).
на публике – emphasizes being in a non-private situation / where other people can see/hear.

So:

Мой брат смело говорит по-русски перед публикой.
– He speaks Russian boldly in front of audiences (as in performances or speeches).
Мой брат смело говорит по-русски на публике.
– He is not shy about speaking Russian when other people are around / in public situations.

Both are correct, but they paint slightly different pictures.

How would the sentence change if I talked about brothers instead of one brother?

You need to change мой брат and говорит to agree in number:

Singular: Мой брат смело говорит по-русски перед публикой.
Plural: Мои братья смело говорят по-русски перед публикой.

Changes:

мой → мои (possessive pronoun, plural)
брат → братья (irregular plural of brother)
говорит → говорят (3rd person plural)

How do you pronounce and stress the words in this sentence?

Stresses (capital letters show the stressed syllable):

мой – moy (one syllable; the vowel is clear)
брат – brat (one syllable; clear vowel)
смЕло – smYE-la (stress on Е)
говорИт – ga-va-REET (stress on the last syllable И; the first о sounds like a in unstressed position: gava-REET)
по-рУсски – pa-ROOS-kee (stress on У; double сс is long)
пЕред – PYER-it (stress on Е; е after п is pronounced like pye)
пУбликой – POO-blee-kay (stress on У)

Putting it together (approximate English-like notation):

Мой брат смЕло говорИт по-рУсски пЕред пУбликой.
Moy brat SMYE-la gava-REET pa-ROOS-kee PYE-red POO-blee-kay.

Is this sentence talking about a one-time event or a general ability?

By itself, Мой брат смело говорит по-русски перед публикой most naturally sounds like a general characteristic or habit:

My brother (in general) is brave about speaking Russian in front of an audience.

If you wanted to highlight one specific event, you’d usually add context:

Сейчас мой брат смело говорит по-русски перед публикой.
– Right now my brother is speaking Russian boldly in front of the audience.

But grammatically the verb form говорит is the same; context is what clarifies it.