Learn Hardcore French: Son stage est mal payé, mais elle apprend beaucoup de choses utiles. - Her internship is poorly paid, but she learns many useful things.

stage is a masculine singular noun: un stage.
For any masculine singular noun, you must use son:
- son stage (her internship / his internship)
- son livre (her/his book)

So:

son stage = her internship (or his internship, depending on context), because stage is masculine.
If the noun were feminine, you’d use sa: sa voiture (her/his car).

Does son mean his or her here?

Son by itself does not mark the gender of the owner; it only matches the gender of the thing owned.

son stage can mean either:
- her internship
- his internship
You know it’s her here only because the subject that follows is elle.

So the sentence tells you the owner is female: elle has son stage.

What exactly does stage mean? Is it like an English stage in a theater?

No. Stage in French is a false friend.

In this sentence, stage = internship, work placement, or training period.
- e.g. faire un stage en entreprise = to do an internship in a company
It does not mean a physical stage (platform in a theater). That would usually be scène in French (la scène).

Why is it mal payé and not mauvais payé?

Because mal is an adverb (“badly, poorly”) and mauvais is an adjective (“bad”).

You use mal to describe how something is done (badly, poorly), often with verbs or past participles:
- bien payé = well paid
- mal payé = badly/poorly paid
Mauvais describes a noun:
- un mauvais stage = a bad internship
- un mauvais café = bad coffee

So with payé (paid), French treats it like a verb result and uses the adverb:

est mal payé = is poorly paid

Why is payé written without an extra e or s?

Agreement here is with stage, which is masculine singular.

son stage → masculine singular
The past participle used as an adjective agrees with the noun:
- masculine singular: payé
- feminine singular: payée
- masculine plural: payés
- feminine plural: payées

Examples:

Son stage est mal payé. (masc. sing.)
Sa formation est mal payée. (fem. sing.)
Ces stages sont mal payés. (masc. plural)

Is est mal payé a passive construction like “is paid badly,” or just an adjective?

It can be seen in two close ways, and both are natural:

Grammatically passive
- Son stage est mal payé ≈ Her internship is (being) poorly paid → as a result of someone paying badly.
Adjectival meaning
- mal payé has become a fixed description meaning badly / poorly paid, like an adjective (low-paid).

In everyday French, people don’t usually think about the grammar; they just understand est mal payé as “is a poorly paid internship.”

Why is it beaucoup de choses and not beaucoup des choses?

After beaucoup, you almost always use de (not des) before a noun:

beaucoup de choses = a lot of things
beaucoup de travail = a lot of work

Beaucoup des is only used in special cases when you’re talking about “many of the … (specific things already known)”, e.g.:

Beaucoup des choses que tu dis sont vraies.
= Many of the things you say are true.

In this sentence, we’re talking in general about “a lot of useful things,” so the normal form is:

beaucoup de choses utiles

What does choses really mean here? Could you just say elle apprend beaucoup?

Chose literally means “thing”, but it’s often used in a vague, general sense, as in English.

beaucoup de choses utiles = a lot of useful things (skills, facts, methods, etc.)

You could say:

Elle apprend beaucoup. = She’s learning a lot.

That is correct French, but it’s less specific. It doesn’t tell you what she’s learning. Adding de choses utiles makes it clear that it’s useful content/skills she is acquiring, not just “learning in general.”

Why is it choses utiles and not utiles choses? How does adjective order work here?

Most French adjectives come after the noun, unlike English.

noun + adjective:
- des choses utiles = useful things
- un livre intéressant = an interesting book

Only a certain group of usually short, common adjectives normally go before the noun (often remembered as BANGS: Beauty, Age, Number, Goodness, Size), such as:

beau, joli, jeune, vieux, bon, mauvais, grand, petit, nouveau, etc.

Since utile isn’t in that group, the default order is:

des choses utiles (correct)
not
des utiles choses (incorrect)

Could you say bien payé instead of mal payé? What’s the contrast?

Yes, bien payé is the positive counterpart of mal payé:

bien payé = well paid
mal payé = badly / poorly paid

Examples:

Son stage est bien payé, et elle apprend beaucoup de choses utiles.
= Her internship is well paid, and she learns a lot of useful things.
Son stage est mal payé, mais elle apprend beaucoup de choses utiles.
= Her internship is poorly paid, but she learns a lot of useful things.

What does mais contribute here? Could you use pourtant instead?

Mais is the basic conjunction “but”, linking two ideas in contrast:

Son stage est mal payé, mais elle apprend beaucoup de choses utiles.
= Her internship is badly paid, but she learns a lot of useful things.

You could also use pourtant (however / yet), but it works a bit differently:

Son stage est mal payé. Pourtant, elle apprend beaucoup de choses utiles.

Differences:

mais:
- simple conjunction inside one sentence
- neutral, very common
pourtant:
- usually starts a new clause/sentence
- sounds a bit more “however / nevertheless,” slightly more emphatic or formal

Both express a contrast between the low pay and the valuable learning.