Le train arrive enfin, et nous y montons rapidement.

The train finally arrives, and we get on it quickly.

Breakdown of Le train arrive enfin, et nous y montons rapidement.

• et: and
• nous: we
• rapidement: quickly
• arriver: to arrive

Questions & Answers about Le train arrive enfin, et nous y montons rapidement.

What does enfin mean here, and why is it placed after arrive?

enfin means finally or at last. When used to modify a verb in French, it can come after the verb without changing the meaning:
Le train arrive enfin = The train finally arrives
You could also put it at the beginning (Enfin, le train arrive), but that shifts the emphasis slightly.

Why is there a comma before et?

In French, a comma can separate two independent clauses, especially when the subject changes. Here the first clause subject is le train, the second is nous, so the comma before et marks the pause between them.

Why do we need nous again in the second part?

Because the subject changes from le train (3rd person) to nous (1st person). French requires an explicit subject pronoun for each finite verb, so you must repeat nous for clarity.

In nous y montons, what does y replace?

y is a pronoun of place that replaces dans le train. It always goes before the verb in simple tenses, so nous y montons literally means we get on it.