Cette formation lui donne la confiance d'une adulte qui connaît bien son métier.

Lui here is an indirect object pronoun meaning to him / to her.

• 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…

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!

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.

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.

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.

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).

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.

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.

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.

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.