Jos pesuohje on epäselvä, kysyn siskoltani, voiko villapaidan pestä käsin.

Jos means if. It introduces a condition:

• Jos pesuohje on epäselvä = If the washing instructions are unclear

This is a very common way to make if-clauses in Finnish. After the jos-clause, the main clause follows.

Pesuohje is a compound noun:

• pesu = washing
• ohje = instruction, guide

So pesuohje means washing instruction or care instruction. Finnish uses compound nouns very freely, much more than English does.

On is the 3rd person singular of olla (to be), and it agrees with the singular subject pesuohje.

• pesuohje on epäselvä = the washing instruction is unclear

Epäselvä is an adjective meaning unclear, ambiguous, or not easy to understand.

Because pesuohje is singular, the verb is singular too:

• ohje on not
• ohje ovat

In Finnish, the subject pronoun is often omitted when the verb ending already shows the person clearly.

• kysyn = I ask
• kysyt = you ask
• kysyy = he/she/it asks

So kysyn already includes the meaning I ask, and minä is not necessary unless you want emphasis.

Siskoltani means from my sister.

It contains three parts:

• sisko = sister
• -lta / -ltä = from someone/something (from the surface or from a person in many common expressions)
• -ni = my

So:

• siskolta = from the sister / from a sister
• siskoltani = from my sister

With kysyä (to ask), Finnish often uses kysyä joltakulta = to ask someone.

So:

• kysyn siskoltani literally = I ask from my sister but in natural English = I ask my sister

Voiko is can + question marker.

It comes from:

• voi = can / is able to
• -ko / -kö = question particle

So:

• voi = can
• voiko = can ... ? / is it possible ... ?

Here it introduces an indirect yes/no question:

• voiko villapaidan pestä käsin = whether the wool sweater can be washed by hand

Even though English uses whether/if, Finnish often uses this -ko/-kö form inside reported or embedded questions.

Finnish often leaves the subject unspecified when English might use something like you, one, someone, or a passive-style idea.

• voiko villapaidan pestä käsin literally looks like can the wool sweater wash by hand
• but really means can the wool sweater be washed by hand

This is a very common Finnish structure:

• Voiko tämän tehdä? = Can this be done?
• Saako täällä istua? = May one sit here? / Can you sit here?

The infinitive pestä works with voida here to express possibility.

Villapaidan is the singular accusative/genitive-looking object form of villapaita (wool sweater).

• base form: villapaita
• object form here: villapaidan

In this sentence, villapaidan is the object of pestä (to wash).

A useful beginner rule is:

• when the action is seen as complete or directed at a whole object, Finnish often uses the total object
• singular total objects often look like the genitive form ending in -n

So:

• pestä villapaitaa would suggest washing some of it / an ongoing or incomplete action in some contexts
• pestä villapaidan refers to washing the whole sweater

Because it depends on voida (can, be able to).

In Finnish, modal verbs like voida are followed by the 1st infinitive:

• voi pestä = can wash
• haluan pestä = I want to wash
• osaan pestä = I know how to wash

So pestä is not finite here; it is the infinitive linked to voiko.

Käsin means by hand.

It comes historically from käsi (hand), but learners usually just memorize käsin as a fixed adverbial expression.

So:

• pestä käsin = to wash by hand

You will often meet it as a set phrase, especially in laundry and care instructions.

Because Finnish uses a comma before a subordinate clause here.

The structure is:

• Jos pesuohje on epäselvä, = conditional subordinate clause
• kysyn siskoltani, voiko villapaidan pestä käsin. = main clause + embedded question clause

Finnish punctuation is often a bit more systematic than English with subordinate clauses, so these commas are important.

Yes, but the given order is natural and neutral.

The sentence is organized like this:

1. condition: Jos pesuohje on epäselvä
2. main action: kysyn siskoltani
3. embedded question: voiko villapaidan pestä käsin

You could move elements around for emphasis, but the original version is the most straightforward for ordinary use.

For example, Finnish could emphasize a different part by changing word order, but a learner should first get comfortable with the neutral pattern shown here.

Yes. Epä- is a common prefix meaning something like un-, in-, or not.

So:

• selvä = clear
• epäselvä = unclear

This is a productive pattern in Finnish, so noticing prefixes can help you guess meanings of new words.

Normally jos means if, not when.

If Finnish clearly means when in a time sense, it usually uses kun:

• Kun pesuohje on epäselvä, kysyn siskoltani... would sound more like When the washing instructions are unclear, I ask my sister...

So in your sentence, jos presents a condition: this happens if that situation occurs.