L'ami d'enfance de Marie vient au dîner.

In French, when le or la (the singular definite articles) comes before a word that starts with a vowel sound (including h muet), it contracts to l' to make pronunciation smoother.

• le ami → becomes l'ami
• Pronunciation: [la-mi], not [lǝ a-mi]

So L'ami d'enfance de Marie means Marie’s childhood friend (male friend).

d'enfance literally means of childhood.

• de = of
• Before a vowel sound, de contracts to d', so de enfance → d'enfance.

The whole phrase l'ami d'enfance is a set expression that means childhood friend (a friend from childhood).

de is used to show possession or a relationship: X de Y = Y’s X.

• l'ami de Marie = Marie’s friend
• l'ami d'enfance de Marie = Marie’s childhood friend

à would indicate something else (often direction, location, or who something is for), not possession.
So l’ami à Marie is incorrect for Marie’s friend.

Yes, you could say:

• Le copain d'enfance de Marie vient au dîner.

Differences:

• ami = friend (neutral, can sound slightly more formal or stronger bond in some contexts)
• copain / copine = friend, mate, buddy; also can mean boyfriend / girlfriend depending on context

In a neutral context about a guest at dinner, ami is clear and slightly more neutral. copain d'enfance is very common in speech, though.

French does not use the English ’s structure.

• English: Marie’s childhood friend
• French: L'ami d'enfance de Marie

Structure: the friend of childhood of Marie (literally).
French keeps de + noun instead of using an apostrophe.

In this sentence:

• vient = comes / is coming (from the verb venir).
• arriver = to arrive.

Both can be used in many situations, but here French naturally prefers venir when emphasizing the movement towards where the speaker is or towards the event:

• L'ami d'enfance de Marie vient au dîner.
  Marie’s childhood friend is coming to the dinner.

Using arriver would focus more on the moment of arrival, and you’d normally add a time:

• L’ami d’enfance de Marie arrive à 20h.
  Marie’s childhood friend arrives at 8 p.m.

à + le contracts to au:

• à le dîner → au dîner

This contraction is mandatory in standard French.
So you must say:

• vient au dîner = is coming to the dinner

Here, dîner is a noun:

• le dîner = the dinner (the meal / the event)

The verb dîner means to have dinner:

• Nous dînons à huit heures. = We have dinner at eight o’clock.

In vient au dîner, au (à + le) clearly marks dîner as a noun (a specific dinner event).

The circumflex in dîner (î) mostly signals historical spelling and pronunciation changes. Historically there was often an s after the vowel (like desjeûner, disner, etc.).

Today:

• dîner is pronounced like dee-né in standard French.
• The î does not change the sound compared to a simple i in this word; it’s more about spelling tradition.

You just need to remember the spelling with î for the noun and the verb dîner.

Yes, vient is the présent de l’indicatif (present indicative).

French present tense covers both English simple present and present continuous:

• L'ami d'enfance de Marie vient au dîner.
  • Marie’s childhood friend comes to the dinner.
  • Marie’s childhood friend is coming to the dinner.

Context decides which English translation fits best. There is no separate continuous form in French like is coming.

Pronunciation in IPA (approximate):

• L'ami d'enfance de Marie → [la.mi dɑ̃.fɑ̃s də ma.ʁi]

Key points:

• L'ami: sounds like la-mi.
• d'enfance: den- with a nasal ɑ̃ (like an in French), then -fance.
• de often reduces to a very short də sound.
• No required liaison between ami and d'enfance, or enfance and de here.

Yes, ami is masculine:

• L'ami d'enfance de Marie = Marie’s (male) childhood friend.

For a female friend, you use amie (with e):

• L'amie d'enfance de Marie vient au dîner.
  • amie = female friend

The article stays L' because both ami and amie start with a vowel. Only the written form shows the gender here.