Aion tehdä varmuuskopion ennen kuin lähden.

Aion is the 1st person singular form of aikoa, which means to intend to or to plan to.

So aion tehdä is a very common Finnish pattern: aikoa + infinitive

That structure is used when you want to say that you intend to do something.

After aikoa, Finnish normally uses the 1st infinitive, which is the basic dictionary form of the verb.

So:

• aion tehdä = I intend to do
• aion lähteä = I intend to leave
• aion ostaa = I intend to buy

You do not conjugate the second verb here, because aion is already the finite verb of the sentence.

Here varmuuskopion is the total object form of varmuuskopio.

Finnish often changes the object case depending on whether the action is seen as:

• complete / finished / whole → total object
• ongoing / incomplete / indefinite → often partitive

In this sentence, the backup is understood as something you intend to complete, so varmuuskopion is natural.

Compare:

• Teen varmuuskopion. = I will make the backup / a backup completely.
• Teen varmuuskopiota. = I am making a backup / working on a backup, with more emphasis on the process or incompleteness.

So the -n ending is not random; it reflects how the action is viewed.

Finnish has no articles, so there is no separate word corresponding to English a, an, or the.

That means varmuuskopion can mean something like:

• a backup
• the backup

The exact interpretation depends on context. Finnish relies much more on context and word endings than English does.

Use ennen kuin when before is followed by a whole clause with a conjugated verb.

Here you have:

• ennen kuin lähden = before I leave

Because lähden is a full verb form, ennen kuin is the right structure.

But if before is followed by a noun or noun-like expression, then ennen alone is enough:

• ennen lähtöäni = before my leaving / before I leave
• ennen matkaa = before the trip

So:

• ennen kuin + clause
• ennen + noun/expression

Finnish does not have a separate future tense in the way English does. The present tense is often used for future meaning when the context makes it clear.

So lähden literally looks like present tense, but in this sentence it clearly refers to a future action:

• ennen kuin lähden = before I leave

The future meaning is understood from the situation and from aion, which already shows intention about a future action.

This is very normal in Finnish.

Finnish usually leaves subject pronouns out when the verb ending already shows who the subject is.

Here:

• aion already means I intend
• lähden already means I leave

So minä is unnecessary unless you want emphasis or contrast.

You could say:

• Minä aion tehdä varmuuskopion ennen kuin lähden.

But that sounds more emphatic, as if you are stressing I.

Yes. Finnish word order is fairly flexible, and you can move the time clause to the front:

• Ennen kuin lähden, aion tehdä varmuuskopion.

This means essentially the same thing, but the emphasis changes a little. Putting ennen kuin lähden first highlights the time frame more strongly.

The original version is also very natural:

• Aion tehdä varmuuskopion ennen kuin lähden.

Yes. That is another natural way to express the same basic idea.

Compare:

• ennen kuin lähden = before I leave
• ennen lähtöäni = before my leaving / before I leave

The first version uses a full clause and feels very straightforward and conversational.

The second version is more compact and a bit more noun-based. It can sound slightly more formal or written, depending on context.

Both are correct.

No. tehdä varmuuskopio is natural, but there are other common ways too.

For example:

• ottaa varmuuskopio = to take a backup
• varmuuskopioida = to back up

So you might also hear:

• Aion ottaa varmuuskopion ennen kuin lähden.
• Aion varmuuskopioida tiedostot ennen kuin lähden.

They are all natural, but varmuuskopioida is especially handy when you want a direct verb meaning to back up.