Kokous alkaa vartin kuluttua.

Vartin is the form of vartti, which means a quarter, usually a quarter of an hour = 15 minutes.

So:

• vartti = a quarter / 15 minutes
• vartin kuluttua = in 15 minutes / after 15 minutes

In this sentence, vartin does not mean quarter in a fraction sense by itself; it is part of a very common time expression.

Because the expression X:n kuluttua requires the time word to be in the genitive.

So:

• vartti → basic form
• vartin → genitive form

This pattern is very common:

• minuutin kuluttua = in a minute
• tunnin kuluttua = in an hour
• päivän kuluttua = in a day
• vartin kuluttua = in a quarter of an hour

So vartin is there because of the grammar used with kuluttua.

Kuluttua is used in expressions meaning after ... has passed or in ... time.

So:

• vartin kuluttua literally means something like after a quarter has passed
• natural English: in 15 minutes

It comes from the verb kulua, which means to pass / elapse about time.

You do not need to analyze it every time, though. It is best to learn X:n kuluttua as one useful time pattern:

• kahden päivän kuluttua = in two days
• viikon kuluttua = in a week
• kolmen tunnin kuluttua = in three hours

Because Finnish usually does not have a separate future tense. It normally uses the present tense when the future meaning is clear from context.

So:

• Kokous alkaa vartin kuluttua. = The meeting starts in 15 minutes. = The meeting will start in 15 minutes.

Both English translations are possible, but Finnish simply uses the present alkaa.

Alkaa means to begin or to start.

Here it is the 3rd person singular present tense:

• minä alan = I begin
• sinä alat = you begin
• hän/se alkaa = he/she/it begins

Since kokous (the meeting) is singular, the verb is alkaa.

So:

• Kokous alkaa = The meeting begins / starts

Because kokous is the subject of the sentence: the meeting is the thing that starts.

In Finnish, subjects are often in the basic dictionary form, called the nominative:

• kokous = meeting
• kokous alkaa = the meeting starts

Nothing special is happening to kokous here; it is just the normal subject form.

This is a very natural, neutral Finnish word order:

• Kokous = subject
• alkaa = verb
• vartin kuluttua = time expression

So it is basically:

The meeting starts in 15 minutes.

Finnish word order is more flexible than English, though. You could also say:

• Vartin kuluttua kokous alkaa.

That puts more focus on when it starts.

So the original sentence is the most neutral version, but not the only possible one.

No, they are different.

• vartin kuluttua = in 15 minutes / after 15 minutes
• vartissa = in 15 minutes in the sense of within a duration

This difference can be tricky because English uses in 15 minutes for both ideas.

Compare:

• Kokous alkaa vartin kuluttua. = The meeting starts in 15 minutes.
  (after 15 minutes from now)

• Teen sen vartissa. = I’ll do it in 15 minutes.
  (it takes me 15 minutes to do it)

So kuluttua tells you about time before something happens, while -ssa/-ssä often tells you how long something takes.

Yes, absolutely.

Both are natural:

• vartin kuluttua = in a quarter of an hour
• 15 minuutin kuluttua = in 15 minutes

The version with vartin is shorter and very common in everyday Finnish. The version with 15 minuutin is a bit more explicit.

It is normal and very common, but it feels a bit more everyday and idiomatic than spelling out 15 minuuttia.

For example, these are all natural:

• odota vartti = wait 15 minutes
• vartin päästä = in 15 minutes
• vartin kuluttua = in 15 minutes
• 15 minuutin kuluttua = in 15 minutes

So vartti is not wrong or slang in a bad sense; it is just a very normal everyday word.

Yes. Vartin päästä and vartin kuluttua are both common ways to say in 15 minutes.

• Kokous alkaa vartin kuluttua.
• Kokous alkaa vartin päästä.

They are very close in meaning. As a learner, you can safely understand both as in 15 minutes.

A rough intuition is:

• kuluttua = after time has elapsed
• päästä = after the passing of time / after a delay

But in everyday use, they often overlap a lot.

You would negate the verb alkaa:

• Kokous ei ala vartin kuluttua. = The meeting does not start in 15 minutes.

Notice that the main verb changes form in Finnish negation:

• positive: alkaa
• negative: ei ala

That is a normal Finnish pattern:

• Kokous alkaa. = The meeting starts.
• Kokous ei ala. = The meeting does not start.

A natural yes/no question would be:

• Alkaako kokous vartin kuluttua? = Does the meeting start in 15 minutes?

Finnish makes this kind of question by adding -ko/-kö to the verb:

• alkaa → alkaako

You could also ask for the time more generally:

• Milloin kokous alkaa? = When does the meeting start?

And answer:

• Kokous alkaa vartin kuluttua.