Learn Hardcore French: Cette formation lui donne la confiance d'une adulte qui connaît bien son métier. - This training gives her the confidence of an adult who knows her job well.

It stands for à lui / à elle (to him / to her).
Its gender is not visible: lui can refer to a man or a woman. Only the broader context (earlier sentences) tells you which.
Grammatically, lui is the person receiving something (the confidence), not the one giving it.

So: Cette formation lui donne… = This training gives him/her…

Why is the word order Cette formation lui donne and not Cette formation donne lui?

In French, object pronouns like lui normally go before the conjugated verb.

Correct: Cette formation lui donne la confiance…
Incorrect: Cette formation donne lui la confiance…

Basic order:

Subject + (object pronoun) + verb + rest of the sentence
Cette formation + lui + donne + la confiance…

You only put donne-lui (verb + pronoun after with a hyphen) in the affirmative imperative:

Donne-lui confiance ! = Give him/her confidence!

What exactly does formation mean here? Is it like education, training, or course?

In this sentence, formation usually means training, course, or professional program, often with a practical/professional focus.

Nuances:

formation: training, vocational or professional preparation, a course of study
éducation: upbringing, moral/social education, broader development
enseignement: teaching, instruction (what teachers do)

So Cette formation is best understood as This (professional) training / this course rather than general education.

Why is it la confiance and not just confiance (without an article) or de la confiance?

Here, la confiance is used as a specific, defined kind of confidence: the confidence of an adult who knows their job well.

donner confiance à quelqu’un = to give someone (some) confidence, make them feel more confident (no article before confiance)
- Cette formation lui donne confiance.
donner la confiance de + groupe nominal = to give someone the (type of) confidence that belongs to a certain person/group
- Cette formation lui donne la confiance d'une adulte…

So:

lui donne confiance = gives him/her confidence (in general).
lui donne la confiance d'une adulte qui connaît bien son métier = gives him/her the confidence that an experienced adult has. It’s more precise and comparative.

How does the structure la confiance d'une adulte work? Is it literally “the confidence of an adult”?

Yes. Grammatically it is:

la confiance = the confidence
d' = of
une adulte = an adult (female)

So la confiance d'une adulte = the confidence of an adult woman.

Semantically, it means the kind of confidence an adult (woman) has, often implying maturity, experience, and assurance.

This is a common structure:

le sourire d’un enfant = the smile of a child
l’attitude d’un professionnel = the attitude of a professional
→ Here: la confiance d’une adulte = the self-assurance of an adult.

Why is it une adulte and not un adulte? Isn’t adulte normally masculine?

Adulte can be masculine or feminine when used as a noun:

un adulte = an adult (man or gender-neutral in some contexts)
une adulte = an adult woman

In this sentence, une adulte clearly refers to a female adult, so the article is feminine:

d'une adulte = of an adult (woman)

Note:

When adulte is an adjective (e.g. une femme adulte), it usually doesn’t change form in writing: adulte looks the same for masculine and feminine.
Here, it is functioning as a noun, so the gender shows only in the article (un / une).

In qui connaît bien son métier, what does qui refer to?

Qui is a relative pronoun that refers back to une adulte.

Structure:

une adulte qui connaît bien son métier
= an adult who knows her job well

So:

qui = who
It is the subject of the verb connaît in the relative clause.
The whole group une adulte qui connaît bien son métier is one noun phrase: an adult who knows her job well.

Why is it son métier and not sa métier, since the adult is a woman?

In French, possessive adjectives (son / sa / ses) agree with the gender and number of the noun possessed, not with the gender of the owner.

métier (job, trade, profession) is masculine singular.
Therefore, you must use son, the masculine singular form:
- son métier = her job / his job (same form in French)

Examples:

sa voiture (car) – because voiture is feminine
son métier (job) – because métier is masculine
Even if the owner is a woman, you still say son métier.

What’s the difference between métier and travail here? Could we say qui connaît bien son travail?

Both métier and travail exist, but they’re not identical:

métier = job, trade, profession; often implies specific skills / trained occupation
- connaître bien son métier = to be very good at one’s trade/profession
travail = work (in general), the activity of working, or work as a thing to do

You could say qui connaît bien son travail, and it would be understandable, but the fixed expression in French is more naturally:

connaître bien son métier = to know one’s profession very well, to be competent and experienced in it.

So the original sounds more idiomatic and emphasizes professional mastery.

Is there a simpler, more common way to express the same idea without la confiance d'une adulte?

Yes. A very natural alternative is to use the common expression donner confiance:

Cette formation lui donne confiance.
= This training gives him/her confidence.

If you want to keep the idea of adult/professional confidence but simpler, you might say:

Cette formation lui donne confiance en elle / en lui.
= This training gives her/him self‑confidence.

The original lui donne la confiance d'une adulte qui connaît bien son métier is stylistically richer and more descriptive, highlighting the specific kind of self-assuredness typical of a competent adult professional.