Kiam amikoj venas, ili eniras nian hejmon kaj ridetas al mia patrino.

the friend

Breakdown of Kiam amikoj venas, ili eniras nian hejmon kaj ridetas al mia patrino.

• ili: they
• kaj: and
• al: to

Questions & Answers about Kiam amikoj venas, ili eniras nian hejmon kaj ridetas al mia patrino.

What exactly does kiam do in this sentence? Is it a question word or something else?

Kiam here is a subordinating conjunction meaning when (in the sense of whenever / at the time that), not a direct question word.

• In direct questions: Kiam vi venos? – When will you come?
• In this sentence it introduces a time clause:
  Kiam amikoj venas, ili eniras nian hejmon… – When friends come, they enter our home…

So kiam works like English when that links two clauses, one describing the time and the other describing what happens then.

Why is it just amikoj and not la amikoj? How do I know if it means friends in general or the friends?

Esperanto has only one definite article, la, and no indefinite article at all.

• amikoj venas can mean:
  • friends come
  • some friends come
  • friends (in general) come
• la amikoj venas means:
  • the friends come (some specific, known group of friends)

In this sentence the idea is general/habitual: whenever friends (not necessarily a fixed group) come, something happens. That is why there is no la. If you wanted to talk about a specific group you have in mind, you would say Kiam la amikoj venas….

All three verbs (venas, eniras, ridetas) are in the present tense. Does that mean this is happening right now?