Quand j’entre, le chiot pose son museau sur mon genou et attend une promenade.

Because je becomes j’ before a vowel sound.

• je entre is not used
• it contracts to j’entre

This is very common in French:

• j’aime
• j’habite
• j’écoute

The verb here is entrer in the je form: j’entre.

French often uses the present tense for actions that happen regularly or as part of a scene being described.

So Quand j’entre, le chiot... can mean:

• When I come in, the puppy...
• Whenever I come in, the puppy...

It does not have to refer only to one specific moment. It can describe a habit or repeated situation.

Quand introduces a time clause, meaning when.

In this sentence, Quand j’entre sets the scene first, and then the main action follows:

• Quand j’entre = when I come in
• main clause: le chiot pose son museau sur mon genou et attend une promenade

So the structure is:

• time clause + main clause

This is very common in French.

The comma separates the introductory time clause from the main clause.

French punctuation here works much like English:

• Quand j’entre, le chiot...

It helps readability. You will often see a comma after a clause placed at the beginning of the sentence.

Le chiot means the puppy, so it refers to a specific puppy already known in the context.

French uses the definite article very often when the speaker and listener both know which thing is being talked about. If the puppy were being introduced for the first time with no prior context, un chiot might be more likely.

So here le chiot suggests:

• this is a particular puppy
• the speaker is talking about a familiar scene or familiar animal

Because museau is a masculine noun.

French possessive adjectives agree with the noun possessed, not with the owner.

So:

• museau is masculine singular
• therefore: son museau

This does not mean the puppy is male. It only reflects the gender of museau.

Compare:

• son museau = his/her/its muzzle
• sa patte = his/her/its paw

Both verbs can involve putting something somewhere, but poser is especially natural for placing or resting something on a surface.

So pose son museau sur mon genou suggests that the puppy gently rests or places its muzzle on the speaker’s knee.

• poser = to place, set down, rest
• mettre = to put

In this context, poser sounds more specific and more natural.

Because the singular form is genou and the plural is genoux.

Here the sentence says on my knee, singular:

• mon genou = my knee
• mes genoux = my knees

French is simply describing the muzzle resting on one knee.

Because genou is masculine.

So the correct possessive adjective is:

• mon genou

As with son museau, the possessive must match the gender and number of the noun:

• mon genou = masculine singular
• ma jambe = feminine singular
• mes genoux = plural

Because attendre is usually a direct transitive verb in French. It takes a direct object.

So you say:

• attendre quelqu’un = to wait for someone
• attendre le bus = to wait for the bus
• attendre une promenade = to wait for a walk

This is different from English, which often needs for.

A common learner mistake is to say attendre pour in cases where standard French simply uses attendre.

It is correct, but learners should know there are several possible words depending on context.

• une promenade often suggests a walk or outing, sometimes leisurely
• une balade is also very common in everyday speech for a walk or outing

So attend une promenade is understandable and correct, but in very natural everyday French, some speakers might also say something like:

• attend sa promenade
• attend une balade
• attend qu’on le promène

The sentence you have is perfectly grammatical; this is just a nuance of usage.

In this sentence, j’entre is best understood as I come in or I enter.

The verb entrer can be used on its own without naming a place if the context is clear:

• J’entre = I come in / I go in / I enter

English usually chooses the most natural translation for the situation. Here When I come in sounds especially natural.