Learn Hardcore French: Le soir, je bois une tisane pour me détendre. - In the evening, I drink an herbal tea to relax.

Le soir, je bois une tisane…
puts the time expression at the beginning for emphasis (similar to In the evening, I drink…).
Je bois une tisane le soir…
is the more neutral word order (I drink a herbal tea in the evening…).

French often puts time expressions (like le soir, le matin, le week‑end) either at the beginning (with a comma) or at the end of the sentence. Both word orders are very natural here.

What exactly does Le soir mean here? Is it this evening or in the evenings?

In this sentence, Le soir means in the evening / in the evenings, i.e. a habitual action.

Le soir, je bois une tisane → I do this regularly in the evenings.
Ce soir, je bois une tisane → This particular evening (tonight), I will drink a herbal tea.

So le soir with the definite article is used for general, repeated times of day:
le matin (in the morning), l’après‑midi, le soir, la nuit.

What is the difference between le soir and la soirée?

They are related but not used the same way:

Le soir = the time of day, evening as a block (around 6 p.m. to bedtime).
Used for habits and time expressions:
Le soir, je lis. – In the evening, I read.
La soirée = the duration or “course of the evening,” often with an activity or event in mind.
Je passe la soirée avec des amis. – I am spending the evening with friends.

In your sentence, you are talking about a regular time of day, so le soir is correct, not la soirée.

Why is it je bois and not some other form? How is boire conjugated?

Bois is the 1st person singular (je) form of the verb boire (to drink) in the present tense.

Present tense of boire:

je bois – I drink
tu bois – you drink (singular, informal)
il / elle / on boit – he / she / one drinks
nous buvons – we drink
vous buvez – you drink (plural or formal)
ils / elles boivent – they drink

So je bois = I drink / I am drinking.

Is there a difference between je bois une tisane and je prends une tisane?

They are very close in meaning here:

Je bois une tisane literally focuses on the act of drinking.
Je prends une tisane is more like I have a herbal tea.

In everyday speech about drinks, prendre is very common:

Je prends un café. – I’ll have a coffee.
On prend un verre ? – Shall we have a drink?

Both versions would be natural in this sentence.

Why is it une tisane and not un tisane? How do I know the gender?

Tisane is a feminine noun in French, so it takes une.

une tisane – a herbal tea / tisane
la tisane – the herbal tea

You cannot guess all genders; they must be learned with the noun.
A good habit is to memorize new nouns with their article:
une tisane, un thé, un café, une soupe, etc.

Why is it une tisane and not something like de la tisane?

Both are possible, but they sound slightly different:

Je bois une tisane.
→ One (whole) tisane, usually one cup/mug. It’s countable here.
Je bois de la tisane.
→ Some tisane in general, more like an unspecified amount of the drink.

In everyday context, when you mean “a cup of herbal tea,” une tisane is very natural.

What exactly is a tisane? Is it the same as thé?

Not exactly.

Un thé = tea made from the tea plant (black tea, green tea, etc.).
Une tisane = a herbal infusion, typically made from herbs, flowers, or fruits (chamomile, verbena, mint, etc.), and often caffeine‑free.

In English we often just say herbal tea for tisane, but in French the distinction is clearer: thé vs tisane.

How does pour me détendre work grammatically? Why pour + infinitive?

Pour + infinitive expresses a purpose or goal: in order to / to.

pour me détendre = in order to relax (myself) / to relax

Structure:

pour = for / in order to
se détendre = to relax (reflexive verb)
With je, se détendre becomes me détendre (because je uses me).

So:

Je bois une tisane pour me détendre.
= I drink a herbal tea in order to relax.

Why is it me détendre and not détendre moi?

Because se détendre is a reflexive verb, and in French reflexive pronouns normally go before the verb (or before the infinitive).

Base form: se détendre
With je: je me détends (present) / pour me détendre (after pour)

You cannot say détendre moi here. Correct patterns:

Je me détends. – I relax.
Je bois une tisane pour me détendre. – I drink a herbal tea to relax.

Can I say pour me relaxer instead of pour me détendre?

It is possible to say se relaxer, but in everyday French se détendre is more natural and more common in this context.

Typical expressions:

Je veux me détendre. – I want to relax.
Ça me détend. – It relaxes me.

Se relaxer is used, but can sound a bit more technical or influenced by English; se détendre is the default everyday choice here.

Why is the verb détendre in the infinitive form and not conjugated, like je me détends?

After pour (when it means “in order to”), French requires the infinitive:

Je bois une tisane pour me détendre.
(pour + infinitive)

If you conjugate it, you must start a new clause:

Je bois une tisane et je me détends. – I drink a herbal tea and I relax.

So:

pour + infinitive → pour me détendre
not pour je me détends.

Why is the present tense used (je bois) if this is a habit?

In French, the present tense is used both for:

Actions happening right now:
Je bois une tisane. – I am drinking a herbal tea (right now).
Regular or habitual actions (like the English simple present):
Le soir, je bois une tisane. – In the evenings, I drink a herbal tea.

Context and time expressions like le soir, tous les jours, souvent show that it’s a habit. You don’t need a special “habitual” tense in French; the present covers this use.