Learn Hardcore Finnish: Minulla on lempikissa.

Finnish usually does not express possession with a verb meaning to have the way English does. Instead, it uses a structure that is literally closer to at me is.

So:

minä = I
minulla = on me / at me
on = is
lempikissa = favorite cat

So Minulla on lempikissa is literally something like At me is a favorite cat, but the natural English meaning is I have a favorite cat.

Why is the verb on and not olen?

This is a very common question.

olen = I am
on = is

In Minulla on lempikissa, the word minulla is not the grammatical subject in the same way English I is. The sentence is built as a possession/existence structure, so Finnish uses on.

Think of it like this:

Minä olen opettaja = I am a teacher
Minulla on kissa = I have a cat

So you use olen when I am the subject of being, but on in this possession pattern.