Learn Hardcore Finnish: Kotivakuutus kattaa irtaimiston. - The home insurance covers the household possessions.

Finnish uses compound words very often, much more freely than English. So instead of writing something like home insurance as two words, Finnish usually makes one word: kotivakuutus.

Why is there no word for the or a in this sentence?

Finnish does not have articles like English a/an and the.

So Kotivakuutus kattaa irtaimiston can be understood as something like:

Home insurance covers the contents
The home insurance covers the contents
A home insurance policy covers the contents

The exact nuance depends on context. Finnish usually leaves that information to the situation rather than marking it with an article.

What form is kattaa here?

Here kattaa is the 3rd person singular present tense of the verb kattaa, meaning covers.

So:

minä kat(an) = I cover
hän kattaa = he/she covers
kotivakuutus kattaa = home insurance covers

A thing that often confuses learners is that the basic form of the verb is also kattaa. In other words, the infinitive and the he/she/it form look the same here. That is normal for many Finnish verbs of this type.