Translation:Kaisa is trying to paint a white cat.
Hmm, a good question. It can mean both actually, it's one of those things you know only from a context. But when I think about this phrase, I imagine her trying to paint an actual cat and in real life I'd usually add something to make sure people understand I mean a painting on a paper, if that's what I mean. Though, people don't often paint cats' fur, hopefully :D
You can't use the object in nominative in this sentence. It has to be either accusative* or dative. Accusative does look like either nominative or genitive, so if she's trying to paint the WHOLE cat, you'd say:
Kaisa yrittää maalata valkoisen kissan.
The partitive indicates the action is either already in process and not finished and we don't know if she will succeed at finishing it or not; or that she doesn't intend to paint the whole cat in the first place but some of it.
´sta´ is the partitive ending to conjugate the word valkoinen. It can be confusing because the ending ´sta´ is also used to mean ´from´, but not in this case.
The partitive is a quite LARGE topic for finish grammar, here you have more information about it: https://uusikielemme.fi/finnish-grammar/grammatical-cases/the-partitive-case-partitiivi
Not quite, I would say that as
- "Kaisa yrittää maalata kissaa valkoisella (värillä)." OR
- "Kaisa yrittää maalata kissaa valkoiseksi."
The first one (adessive case) roughly means "with a white color" and the second one is translative case which expresses the action of becoming or turning into something. I think this is what your original idea was too, so it means that she is trying to paint the cat so it will become white.
"Kissaa" is a partitive singular form, so it can only be singular. However, it can refer to multiple referents when it's in a noun phrase that contains a word that expresses a number or quantity. In this particular sentence, it has only one referent. The partitive case is applied to it firstly because it is the object of the clause, and secondly because it is acted upon by a verb that expresses an ongoing action. If there were several referents, the partitive plural form "valkoisia kissoja" would be used instead because there isn't a word in the noun phrase that specifies the number or quantity.