Ennen kuin lähden töihin, tarkistan vielä, että kuivaushuoneen ovi on kiinni ja varastokomero lukossa.

Ennen kuin means before when it introduces a whole clause, as in before I leave for work.

• ennen on its own can mean before / earlier
• kuin is used to connect it to a clause

So:

• ennen töitä = before work
• ennen kuin lähden töihin = before I leave for work

In other words, Finnish uses ennen kuin where English uses before + a full clause.

Finnish often uses the present tense to talk about the future when the time is clear from context.

So ennen kuin lähden töihin literally looks like before I leave to work / before I am leaving to work, but in natural English it is before I leave for work.

This is completely normal in Finnish. There is no separate future tense in everyday Finnish.

Lähteä töihin is a very common fixed expression meaning to leave for work / go to work.

Even though työ is singular in dictionary form, Finnish often uses the plural form in this expression:

• mennä töihin = go to work
• lähteä töihin = leave for work
• olla töissä = be at work

Here:

• töihin is the illative plural form, meaning roughly into work / to work

Using työhön is possible in some contexts, but it usually sounds more like into a job/task/position, not the everyday routine meaning go to work.

Here vielä means something like still, yet, or one more time before that.

In this sentence, it gives the sense:

• I still check
• I check once more
• I check first / before leaving

So tarkistan vielä suggests a final check before going out.

Vielä is a very flexible word, and its exact English translation depends on context.

Että introduces a content clause, often translated as that.

So:

• tarkistan, että... = I check that...
• varmistan, että... = I make sure that...

In this sentence, the speaker is checking that the drying-room door is closed and the storage cupboard locked.

In English, that is often optional, but in Finnish että is very commonly used in this kind of structure.

Kuivaushuoneen is in the genitive singular.

This is how Finnish commonly expresses the door of the drying room:

• kuivaushuone = drying room
• kuivaushuoneen ovi = the drying room’s door / the door of the drying room

The pattern is:

• owner/location/whole in genitive
• main noun in nominative

More examples:

• talon ovi = the house’s door / the door of the house
• auton avain = the car’s key / the key to the car

So kuivaushuoneen ovi is a very normal Finnish noun phrase.

Kuivaushuone is a compound noun:

• kuivaus = drying
• huone = room

So kuivaushuone is literally drying room.

In many buildings in Finland, especially apartment buildings, this can mean a shared room for drying laundry.

Finnish uses compound nouns very freely, so long words like this are very common.

Yes, here kiinni means closed/shut.

With doors, windows, lids, etc., olla kiinni is the usual everyday way to say that something is closed:

• ovi on kiinni = the door is closed
• ikkuna on kiinni = the window is closed

It can also mean attached or stuck to in other contexts, so the basic idea is something like fastened/closed/in contact.

For a door, though, on kiinni is the normal phrase for is closed.

The second on is simply omitted because it is understood from the first part.

Full version:

• kuivaushuoneen ovi on kiinni ja varastokomero on lukossa

Actual sentence:

• kuivaushuoneen ovi on kiinni ja varastokomero lukossa

This is very natural in Finnish. When two coordinated parts share the same verb, the verb is often left out in the second part.

So English would still translate it as:

• the drying-room door is closed and the storage cupboard is locked

Lukossa comes from lukko, meaning lock.

• lukko = lock
• lukossa = in the lock

But as an expression, olla lukossa means to be locked.

So this is one of those Finnish state expressions where a case form is used idiomatically:

• ovi on lukossa = the door is locked
• pyörä on lukossa = the bike is locked

The ending -ssa is the inessive case, usually meaning in. Literally it sounds like in lock, but idiomatically it just means locked.

They are related, but not the same.

• kiinni = closed / shut
• lukossa = locked

A door can be:

• kiinni mutta ei lukossa = closed but not locked
• auki = open
• lukossa = locked

So in the sentence, the speaker checks two different things:

• the drying-room door is closed
• the storage cupboard is locked

Because Finnish forms compound nouns very productively.

• varasto = storage
• komero = cupboard / closet / cabinet

Together:

• varastokomero = storage cupboard / storage closet

This is extremely normal in Finnish. Where English may use two words, Finnish often prefers one compound word.

The commas separate subordinate clauses from the main clause.

Sentence structure:

• Ennen kuin lähden töihin, = subordinate clause
• tarkistan vielä, = main clause
• että kuivaushuoneen ovi on kiinni ja varastokomero lukossa. = subordinate että clause

Finnish normally uses commas before and/or after subordinate clauses more consistently than English does.

So the commas here are standard and expected.