Szara is the feminine singular form of the adjective szary (gray).
Adjectives in Polish must agree with the noun in:
Because spódnica is:
the adjective also takes the feminine singular nominative form:
So:
Because after do, the noun usually goes into the genitive case.
The basic form is:
But in this sentence, we have:
That is the genitive singular form of both the adjective and the noun.
So the pattern is:
This happens because pasować do means to go well with / to match, and do requires the genitive.
Pasować do means to match, to suit, or to go well with.
In clothing contexts, it often means that one item looks good with another:
It is a fixed pattern:
So you do not say just pasuje białą bluzkę.
You say:
Because spódnica is the subject of the sentence, while bluzki is part of the phrase after do.
In this sentence:
So:
Yes. Pasuje is the 3rd person singular form of pasować.
The subject is:
That subject is singular, so the verb is singular:
If the subject were plural, the verb would change:
Yes. Polish word order is more flexible than English word order because endings show grammatical relationships.
The neutral, natural order here is:
But other orders are possible, especially for emphasis, for example:
Do białej bluzki pasuje ta szara spódnica. = emphasis on with the white blouse
Ta szara spódnica do białej bluzki pasuje. = more marked, stylistic, or contrastive
Even though these versions are possible, the original sentence is the most natural choice for a learner.
Because it is the feminine singular genitive form of the adjective biały (white).
Here are the relevant forms:
Since bluzka is feminine, and since do requires the genitive, the adjective must also be feminine genitive:
This is normal adjective agreement in Polish.
It is singular here.
That can be confusing, because bluzki can also be a plural nominative/accusative form in other contexts.
But in this sentence, bluzki is:
You can tell from the phrase:
Both words are feminine singular genitive:
So the meaning is:
You can, but it does not mean exactly the same thing.
For clothing combinations, pasuje do is the most natural and idiomatic choice.
So:
Polish often does not use articles like the or a, because Polish has no articles.
So the same sentence can often mean either:
If you want to remove the sense of this, you can say:
That can mean:
Context usually makes it clear.
A rough English-friendly pronunciation is:
A few useful notes:
So:
The exact Polish sounds are a bit different from English, but that approximation is a good start.