De retour en ville, Marie achète un bracelet connecté pour suivre son sommeil.

Literally it is “back in town”.

Grammatically:

• de
  • a noun (retour) is a very common way in French to say “being …” / “when … is … again”.
• retour is a noun meaning return.
• So De retour en ville = (Being) back in town / Once (she is) back in town.

It’s an elliptical structure: the subject and verb are understood:

• Full idea: Quand Marie est de retour en ville, …
• Shortened: De retour en ville, Marie …

French often uses this pattern:

• De retour à la maison, il se douche. = Back home, he takes a shower.
• Devenu célèbre, il voyage beaucoup. = Having become famous, he travels a lot.

Because French uses the fixed expression être de retour (to be back), not être à retour.

Examples:

• Je suis de retour. = I’m back.
• Ils seront de retour demain. = They’ll be back tomorrow.

So when you shorten Quand Marie est de retour en ville, you keep de retour, not à retour:

• ✅ De retour en ville, Marie achète…
• ❌ À retour en ville, Marie achète… (incorrect)

En ville is an idiomatic expression meaning:

• in town / in the city (as opposed to the countryside or suburbs)
• often with no specific town in mind.

À la ville can exist, but it’s much less common and usually contrasts with something like à la campagne in a more abstract, sociological way (city life vs country life), or it’s tied to a specific city in some contexts.

In this sentence, Marie is simply back in town, so en ville is the natural, everyday choice:

• Je vais en ville. = I’m going into town.
• J’habite en ville. = I live in town / in the city.

You can move it:

• Marie, de retour en ville, achète un bracelet connecté…
• Marie achète, de retour en ville, un bracelet connecté… (possible but heavier)

However, the original:

• De retour en ville, Marie achète…

is very natural and stylistically clean. Putting De retour en ville at the beginning:

• sets the context first (where/when)
• then introduces the action.

In isolation, both are possible:

• Marie achète un bracelet connecté…

  • Present tense
  • Can be:
    • a general present (she is buying one now),
    • or a historic/narrative present, used to make a story feel more vivid:
      De retour en ville, Marie achète… puis elle rentre chez elle…

• Marie a acheté un bracelet connecté…

  • Passé composé (past event)
  • Neutral description of a completed action in the past.

So:

• For everyday conversation about a past event: Marie a acheté…
• For storytelling or describing a scene “as if it were happening now”: Marie achète… is very common and stylistically strong.

Pronunciation: roughly [a-ʃɛt]:

• a like a in father
• ch like sh in she
• è like e in bed
• final t is silent

Spelling:

• The verb is acheter (to buy).
• In je/tu/il/elle/on/ils/elles in the present, the vowel changes:
  • j’achète, tu achètes, il/elle achète, ils/elles achètent
  • but nous achetons, vous achetez (no accent, original vowel)

The accent grave (è) marks that the vowel is open [ɛ] and also reflects this regular stem change pattern.

A bracelet connecté is a connected bracelet, i.e. a smart bracelet / fitness tracker that connects to your phone or the internet.

It’s not just a decorative bracelet:

• it usually tracks steps, heart rate, sleep, etc.
• it syncs data to a smartphone app.

So in context, it’s like saying:

• Marie buys a smart bracelet to track her sleep.

Because bracelet is masculine in French:

• un bracelet (a bracelet)
• le bracelet (the bracelet)
• mon bracelet (my bracelet)

Adjectives must agree in gender and number with the noun:

• un bracelet connecté
  (masculine singular noun + masculine singular adjective)

If the noun was feminine, both would be feminine:

• une montre connectée = a smart watch
  (montre is feminine, so une and connectée get -e)

In French, most adjectives normally come after the noun:

• un bracelet connecté
• une voiture rouge (a red car)
• un téléphone portable (a mobile phone)

Some short/common adjectives often come before the noun (e.g. beau, grand, petit, bon, mauvais, jeune, vieux), but connecté is not one of them, so it follows the usual rule: adjective after noun.

Literally:

• pour = for / in order to
• suivre = to follow
• son sommeil = his/her sleep

So pour suivre son sommeil = to follow her sleep
In natural English: to track/monitor her sleep.

The structure pour + infinitive expresses purpose:

• pour suivre = in order to track

Yes, suivre, surveiller, and contrôler are all used in health/tech contexts, but with slightly different flavors:

• suivre son sommeil

  • very common for data/metrics
  • like to track / monitor over time
  • neutral, often used for apps and devices

• surveiller son sommeil

  • more like to watch over / keep an eye on
  • slightly more active/attentive nuance

• contrôler son sommeil

  • to control / regulate your sleep
  • can sound like trying to manage or keep it under control, not just observe it

For a fitness tracker or smart bracelet, suivre son sommeil is the most natural and frequent expression.

In French, possessive adjectives (mon/ma/mes, ton/ta/tes, son/sa/ses) agree with the gender and number of the noun possessed, not with the owner.

• sommeil (sleep) is masculine singular.
• So you must use son (masculine singular possessive):
  • son sommeil = her sleep / his sleep

If the noun were feminine:

• sa montre = her watch / his watch (montre is feminine)
• sa voiture = her car / his car

So:

• ✅ son sommeil (correct: masculine noun)
• ❌ sa sommeil (wrong: sommeil is not feminine)

With pour expressing purpose, French uses directly: pour + infinitive, with no extra preposition:

• pour suivre son sommeil = to track her sleep
• pour apprendre le français = to learn French
• pour comprendre, il faut pratiquer = to understand, you must practise

So:

• ✅ pour suivre
• ❌ pour à suivre (incorrect)