Learn Hardcore French: Ses colocataires trouvent Marie très sympa quand elle fait la vaisselle pour tout le monde. - Her roommates find Marie very nice when she does the dishes for everyone.

son = his/her/its + masculine singular noun (e.g. son frère – his/her brother)
sa = his/her/its + feminine singular noun (e.g. sa sœur – his/her sister)
ses = his/her/its + plural noun (e.g. ses colocataires – his/her roommates)

In this sentence, ses colocataires = her roommates (because we’re talking about Marie), but grammatically ses itself does not tell you whether it’s “his” or “her” – you get that only from context.

How do we know ses means “her” roommates and not “his” roommates?

French possessives for the 3rd person singular (son, sa, ses) do not show the owner’s gender. They only show:

number and gender of the thing owned, not the owner.

So in isolation, ses colocataires could mean:

his roommates
her roommates
its roommates (theoretically)

We know it’s “her roommates” here only because Marie is the person being talked about. The context makes it clear that the roommates belong to Marie.

What exactly does colocataires mean? Is it more like “roommates” or “flatmates”?

Un/une colocataire (often shortened to un/une coloc) is someone you share accommodation with. It corresponds to:

“roommate” (US English)
“flatmate” or “housemate” (UK English)

Forms:

singular masculine: un colocataire
singular feminine: une colocataire
plural (mixed group or unknown gender): des colocataires

In this sentence, Ses colocataires = her roommates/flatmates.

Why is it trouvent Marie très sympa and not something like pensent que Marie est très sympa?

French often uses trouver + direct object + adjective to mean “to find [someone] [adjective] / to consider [someone] [adjective]”.

Ses colocataires trouvent Marie très sympa.
= Her roommates find Marie very nice / think Marie is very nice.

You could say:

Ses colocataires pensent que Marie est très sympa.

This is also correct, but:

trouver + adj is more idiomatic and natural in everyday speech for giving a personal impression about someone or something.
penser que… is a bit more literally “to think that…”, and can sound slightly more detached or abstract.

So trouver Marie très sympa is the most natural, conversational choice here.

What nuance does sympa have? Is it the same as “nice” or “kind,” and how does it compare to gentille or sympathique?

Sympa (short for sympathique) usually means something like:

nice / friendly / pleasant / likeable

Nuance:

It’s informal and very common in everyday speech.
It describes someone who gives you a good, easy-going impression and is pleasant to be around.

Comparisons:

sympathique: the full, slightly more formal version; still common, but sympa is more colloquial.
gentil / gentille: emphasizes kindness, being helpful or considerate (doing good things for others).
aimable: more like “civil / courteous / polite”, sometimes a bit formal.

So très sympa here mainly implies “really nice and pleasant (as a person)” rather than specifically “kind-hearted” or “polite.”

Does sympa change form for feminine or plural?

Historically and in standard usage, sympa is invariable in gender and usually treated as invariable in number:

masculine singular: un garçon sympa
feminine singular: une fille sympa
masculine plural: des garçons sympa (traditional)
feminine plural: des filles sympa (traditional)

However, in modern French, especially informally, you will often see sympas used as a plural form:

des voisins sympas
des filles sympas

Both sympa and sympas in the plural are generally accepted; some style guides prefer sympa invariable, but everyday usage strongly favors sympas for plural. There is no feminine form like “sympate” – that doesn’t exist.

Why is it fait la vaisselle and not something like lave les assiettes?

In French, the natural idiom for “to do the dishes” is:

faire la vaisselle = literally “to do the dishes / the washing up”

You could say laver la vaisselle, but:

faire la vaisselle is the normal, idiomatic expression.
laver les assiettes would only mean “wash the plates” specifically and sounds too narrow in this context (it excludes glasses, cutlery, pans, etc.).

So quand elle fait la vaisselle is the standard way to say “when she does the dishes / the washing up.”

Why do we say la vaisselle with la? Why not just faire vaisselle?

In French, la vaisselle is a noun meaning both:

the dirty dishes themselves, and
the activity of washing them (by metonymy).

French usually requires an article (le, la, les) before countable and many mass nouns:

faire la cuisine (to cook / do the cooking)
faire le ménage (to do the housework)
faire la lessive (to do the laundry)
faire la vaisselle (to do the dishes)

You cannot normally drop the article here, so faire vaisselle is incorrect. It must be faire la vaisselle.

Why is the present tense used in quand elle fait la vaisselle? Could it also refer to the future?

In French, quand + présent is used:

for habitual/general actions:
- Quand elle fait la vaisselle, ils sont contents.
  = Whenever/When she does the dishes, they are happy.
also for future in many cases:
- Quand elle fait la vaisselle demain, ils seront contents.
  = When she does the dishes tomorrow, they will be happy.

So quand elle fait la vaisselle in the given sentence expresses a repeated, habitual situation: whenever she does the dishes for everyone, her roommates find her very nice. French does not require a special future tense after quand the way English often does.

Could we say lorsqu’elle fait la vaisselle instead of quand elle fait la vaisselle? Is there a difference?

Yes, you can say:

Ses colocataires trouvent Marie très sympa lorsqu’elle fait la vaisselle pour tout le monde.

lorsque and quand are very close in meaning:

Both usually mean “when” (in the temporal sense).
lorsque is often felt as a little more formal or written; quand is more neutral and frequent in speech.

In this sentence, the meaning is the same. Using lorsque would just sound a touch more formal or literary, but still perfectly natural.

What does pour tout le monde literally mean, and why do we use pour here instead of à?

Literally, pour tout le monde means:

“for everyone” (word for word: for all the world)

Breakdown:

pour = for (indicating who benefits from the action)
tout le monde = everybody / everyone (grammatically singular)

We use pour here because Marie is doing something for the benefit of other people:

Elle fait la vaisselle pour tout le monde.
= She does the dishes for everyone (on everyone’s behalf).

Using à (à tout le monde) would change the meaning to something like “to everyone,” used with verbs like:

parler à tout le monde (to talk to everyone)
offrir un cadeau à tout le monde (to give a present to everyone)

So pour tout le monde is correct and idiomatic with faire la vaisselle.

Why do we use elle in quand elle fait la vaisselle instead of repeating Marie?

In French (as in English), once a person has been clearly identified, it’s natural to refer to them with a pronoun instead of repeating the name:

Ses colocataires trouvent Marie très sympa quand elle fait la vaisselle…
= Her roommates find Marie very nice when she does the dishes…

Here:

Marie is first introduced as the direct object of trouvent.
Then elle (she) clearly refers back to Marie as the subject of fait la vaisselle.

You could repeat the name:

…quand Marie fait la vaisselle…

This isn’t grammatically wrong, but it sounds heavier and more repetitive. Using elle is the normal, natural choice once the reference is clear.