Je vais chez ma sœur après le travail.

Because French verbs have to be conjugated.

The base form is aller = to go.
In a full sentence, you need the form that matches the subject:

• je vais = I go / I am going
• tu vas = you go
• il/elle va = he/she goes

So Je vais chez ma sœur literally uses the present tense of aller.

It can mean either one, depending on context.

French simple present often covers both:

• I go
• I am going

So Je vais chez ma sœur après le travail could mean:

• I go to my sister’s place after work (habit)
• I’m going to my sister’s place after work (today/soon)

If you want to make the future idea extra clear, French can also use:

• Je vais aller chez ma sœur après le travail = I’m going to go to my sister’s place after work

But in everyday French, Je vais chez ma sœur après le travail is very natural.

Chez is a very common French preposition meaning something like:

• at the home of
• to the place of
• at/to someone’s place

So chez ma sœur means to my sister’s house/place or at my sister’s place.

French usually does not say à ma sœur for this meaning.
À ma sœur would usually mean to my sister in the sense of giving something to her, not going to her home.

No. Chez is used with people, but also with places associated with people, such as businesses or professionals.

For example:

• chez le médecin = at the doctor’s / to the doctor’s
• chez le coiffeur = at the hairdresser’s / to the hairdresser’s
• chez Paul = at Paul’s place
• chez mes parents = at my parents’ house

So in chez ma sœur, the idea is my sister’s place, not necessarily only her literal house.

Because sœur is a feminine noun, so the possessive adjective must match the noun being possessed:

• mon frère = my brother
• ma sœur = my sister

In French, possessive adjectives agree with the thing/person possessed, not with the owner.

So:

• ma sœur = my sister
• ma mère = my mother
• mon père = my father

One thing to remember: before a feminine noun starting with a vowel sound, French often uses mon instead of ma for pronunciation:

• mon amie = my female friend

But sœur starts with a consonant sound, so it stays ma sœur.

Sœur means sister.

The spelling can look unusual to English speakers because of the œ ligature. It is pronounced roughly like the vowel in French peur or somewhat like the vowel in English bird, but not exactly the same.

A simple learner-friendly approximation is something like:

• sur, but with a French vowel

The r at the end is the French r, not a strong English r.

Because French usually uses an article where English often does not.

English says:

• after work

French says:

• après le travail

This is very normal. French often prefers:

• le travail = work
• l’école = school
• la maison = home/house

So even though English drops the, French often keeps it.

Yes, but it means something slightly different.

• après le travail = after work, after the workday, after getting off work
• après mon travail = after my work, after my task/job/work that I have to do

So if you mean the general daily routine after work, après le travail is the most natural choice.

Because in French, time expressions often come after the main idea, especially in simple everyday sentences.

So the order:

• Je vais chez ma sœur après le travail

is very natural.

It is basically:

• I’m going to my sister’s place
  • after work

You could move it for emphasis in some contexts, but the original order is the most neutral and common.

Yes, but it is less natural in most everyday situations.

• chez ma sœur = natural, idiomatic, common
• à la maison de ma sœur = more literal, more specific, and heavier

French strongly prefers chez when talking about going to or being at someone’s place.

So a native speaker would normally say:

• Je vais chez ma sœur

rather than:

• Je vais à la maison de ma sœur

Here it means going to your sister’s place, because of the verb vais from aller.

• Je vais chez ma sœur = I’m going to my sister’s place

But chez itself can work with both ideas depending on the verb:

• Je suis chez ma sœur = I’m at my sister’s place
• Je vais chez ma sœur = I’m going to my sister’s place

So the verb tells you whether it is location or destination.

Yes, a few things may matter to learners:

• Je is often pronounced very lightly.
• vais sounds like vay
• chez sounds roughly like shay
• ma sœur is said smoothly together
• après le travail is also linked naturally in speech

Also, in normal speech, French rhythm groups words together, so the sentence flows rather than sounding word-by-word:

• Je vais | chez ma sœur | après le travail

Listening practice is especially helpful with a sentence like this because the written form is a bit more formal-looking than the spoken rhythm.