Learn Hardcore French: Un enfant commence à paniquer, mais sa mère lui parle doucement. - A child starts to panic, but his mother speaks to him gently.

Un enfant = a child (grammatically masculine, but the child could be a boy or a girl).
If you really want to specify:
- un garçon = a boy
- une fille = a girl

French often defaults to the masculine form (un enfant) when speaking in general or when the gender is irrelevant to the story. You can say une enfant, but it’s much less frequent and sounds more marked/literary.

Why is it commence à paniquer and not commence de paniquer or something else?

With commencer plus a verb, French commonly uses commencer à + infinitive:

commencer à paniquer = to begin/start to panic

Most of the time, when another verb follows commencer, you use à. You will see commencer de as well, but:

commencer à + infinitive is more frequent, especially in everyday spoken French.
commencer de + infinitive is more literary/formal and limited in use.

So here commence à paniquer is the natural, standard way to say starts panicking.

Why is it paniquer and not something like se paniquer? Shouldn’t it be reflexive?

Paniquer is not a reflexive verb in French; it’s just a normal (non-reflexive) -er verb.

Un enfant panique. = A child panics.
Un enfant commence à paniquer. = A child is starting to panic.

There is no reflexive form like se paniquer in standard French. If you want a reflexive expression with a similar idea, you might use:

s’affoler = to get flustered, to panic
s’angoisser = to become anxious

But paniquer itself stands alone: it does not take se.

How do you conjugate paniquer in the present tense? Are there any spelling changes?

Yes, paniquer has a small spelling change to keep the [k] sound before o and a. Here is the present tense:

je panique
tu paniques
il / elle / on panique
nous paniquons
vous paniquez
ils / elles paniquent

Notice:

The -qu- in nous paniquons ensures the pronunciation stays [pani-kɔ̃] instead of turning into something like [pani-sɔ̃].
Otherwise, it’s a regular -er verb.

In the sentence, commence à paniquer uses the infinitive (non-conjugated form) after commence à.

Why is it sa mère and not son mère? I thought son meant “his/her.”

In French, son / sa / ses agree with the thing owned, not with the owner.

mère is a feminine noun, so you must use sa.
- sa mère = his mother / her mother
son is used when the possessed noun is masculine:
- son père = his father / her father
ses is used when the possessed noun is plural:
- ses parents = his parents / her parents

So sa mère is correct because mère is feminine singular.

How can I tell if sa mère means “his mother” or “her mother”?

You can’t tell just from sa mère itself.

sa mère can mean either his mother or her mother.
The pronoun only shows that the possessor is third person singular (he/she/it/that person), and that the noun (mère) is feminine singular.

To know whether it’s “his” or “her,” you need context from the wider text or conversation.

What does lui mean in sa mère lui parle doucement, and why does it go before the verb?

Here, lui is an indirect object pronoun meaning to him / to her.

parler à quelqu’un = to speak to someone
The indirect object à un enfant becomes the pronoun lui:
- Sa mère parle à un enfant.
- Sa mère lui parle. = His/her mother speaks to him/her.

In French, object pronouns like me, te, lui, nous, vous, leur usually go before the conjugated verb:

Elle lui parle. = She speaks to him/her.
Elle lui parle doucement. = She speaks gently to him/her.

So the order lui parle is normal and mandatory in standard French.

Why is it lui parle and not parle à lui?

Parler à lui is grammatically possible, but it’s used only in special emphatic cases, for example:

C’est à lui que je parle, pas à toi. = It’s to him that I’m talking, not to you.

In a neutral sentence, French strongly prefers pronouns before the verb:

Neutral/normal: Sa mère lui parle doucement.
Emphatic/contrastive: Sa mère parle à lui, pas aux autres.

So for a simple sentence like the one you have, lui parle is the correct and natural structure.

What kind of word is doucement, and why isn’t it douce here?

Doucement is an adverb meaning gently / softly / quietly.

doux / douce = adjective: gentle / soft
- une voix douce = a gentle voice
doucement = adverb: gently / softly
- parler doucement = to speak gently

In French, adverbs often end in -ment and are used to describe how an action is done. Since doucement describes how she speaks, you need the adverb form, not the adjective.

Can doucement go somewhere else in the sentence, like sa mère parle doucement lui?

You can move doucement a bit, but not just anywhere. Acceptable placements here include:

Sa mère lui parle doucement. (most natural)
Sa mère lui parle très doucement. (with an intensifier)

What you cannot say in standard French is:

✗ Sa mère parle doucement lui.

French object pronouns (lui, leur, me, etc.) go before the verb (or before the auxiliary in compound tenses). The adverb typically comes after the verb in a simple tense like this.

Why is the whole sentence in the present tense? Could we say est en train de paniquer instead?

The present tense in French is often used to describe actions happening right now, just like in English narrative:

Un enfant commence à paniquer.
= A child starts panicking / is starting to panic.

You can say:

Un enfant est en train de paniquer.
= A child is in the middle of panicking.

But that changes the nuance a bit:

commence à paniquer focuses on the beginning of the panic.
est en train de paniquer focuses on the ongoing process of panicking.

Both use the present; they just highlight different moments of the action.

Is mais used exactly like “but” in English here?

Yes, mais is the standard conjunction meaning but.

Un enfant commence à paniquer, mais sa mère lui parle doucement.
= A child starts to panic, but his/her mother speaks to him/her gently.

It introduces a contrast: the child’s panic vs. the mother’s calm reaction.

Mais is very common and neutral in register, used in both spoken and written French, just like but in English. There are other conjunctions for contrast (like pourtant, cependant, en revanche), but here mais is the simplest and most natural.