Me hice daño en el labio porque estaba nerviosa antes de hablar en público.

It means I hurt myself or I injured myself.

The expression hacerse daño is very common in Spanish. Literally, it is something like to do harm to oneself:

• hacer daño = to hurt / to cause harm
• hacerse daño = to hurt oneself
• me hice daño = I hurt myself

In this sentence, en el labio tells you where the injury was.

Me shows that the person affected is the same person as the subject.

So:

• hice daño = I caused harm
• me hice daño = I hurt myself

Without me, the meaning changes completely.

Hice is the preterite form of hacer for yo.

It is used because the injury is seen as a completed event in the past: at some point, the speaker hurt her lip.

Also, hacer is irregular in the preterite:

• hice
• hiciste
• hizo
• hicimos
• hicisteis
• hicieron

Because hacerse daño is an idiomatic and very natural Spanish expression.

English often uses hurt directly, but Spanish often prefers:

• me hice daño = I hurt myself
• se hizo daño = he/she hurt himself/herself

You may also hear other verbs, such as lastimarse or herirse, but hacerse daño is extremely common and very natural.

Spanish often uses the definite article with body parts when it is already clear whose body part it is.

Since me already tells us the lip belongs to the speaker, Spanish normally says:

• me hice daño en el labio

rather than:

• me hice daño en mi labio

Using mi is possible, but it would usually sound more emphatic or contrastive.

Because the sentence refers to one lip.

So:

• el labio = the lip / my lip
• los labios = the lips / my lips

If both lips were meant, Spanish would normally say los labios.

Because estar is used for a temporary state, while ser would describe a more general characteristic.

Here, the speaker was nervous at that moment, before speaking in public, so Spanish uses:

• estaba nerviosa = I was feeling nervous

But:

• era nerviosa would mean something more like I was a nervous person by nature or I used to be generally nervous

Estaba is the imperfect, and it gives background information: it describes the speaker’s emotional state at the time.

The sentence has:

• a main event: me hice daño
• a background state/reason: estaba nerviosa

That is why the combination feels natural:

• me hice daño = completed action
• estaba nerviosa = ongoing state in the background

Using estuve nerviosa would sound more like a completed, bounded period of being nervous, which is less natural in this sentence.

Because the adjective agrees with the speaker’s gender.

• nerviosa = used by a female speaker
• nervioso = used by a male speaker

So if a man said the same sentence, it would be:

Me hice daño en el labio porque estaba nervioso antes de hablar en público.

Because Spanish often omits subject pronouns when they are already clear from the verb form.

Here, hice already tells you the subject is I.

So:

• Me hice daño... = perfectly normal
• Yo me hice daño... = also possible, but more emphatic

Spanish includes yo only when it is needed for emphasis, contrast, or clarity.

Because after antes de, Spanish uses an infinitive when the subject is the same.

So:

• antes de hablar = before speaking

This is the normal pattern:

• antes de salir = before leaving
• antes de comer = before eating

If the subject changes, Spanish usually uses antes de que + subjunctive instead:

• antes de que ella hablara = before she spoke

It means to speak in public or to speak before an audience.

It does not necessarily mean speaking outdoors or in a public place. It usually means speaking where other people are watching or listening, like in a presentation, speech, or formal talk.

So hablar en público is a very common way to express public speaking.

Because porque means because.

• porque = because
• por qué = why

So in this sentence:

• porque estaba nerviosa = because I was nervous

If it were a question, then you would use por qué:

• ¿Por qué estabas nerviosa? = Why were you nervous?

Yes. A few natural alternatives are possible, depending on the exact meaning:

• Me hice daño en el labio = I hurt my lip / I hurt myself on the lip
• Me lastimé el labio = I hurt my lip
• Me mordí el labio = I bit my lip

The last one is more specific. If the speaker hurt her lip by biting it out of nerves, me mordí el labio would be very precise. But me hice daño en el labio is broader and still very natural.