Kun surullinen elokuva loppuu, pyyhin kyyneleen ja juon teetä.

Here, kun means when and introduces a time clause:

Kun surullinen elokuva loppuu = When a sad movie ends

In other contexts, kun can sometimes mean because/since, but in this sentence the time meaning is the natural one.

Because Kun surullinen elokuva loppuu is a subordinate clause, and it comes before the main clause.

So Finnish punctuation works like this:

Kun surullinen elokuva loppuu, pyyhin kyyneleen ja juon teetä.

A comma separates the subordinate clause from the main clause.

Because loppua means to end in the sense that something ends by itself, while lopettaa usually means to end/stop something.

• Elokuva loppuu = The movie ends
• Lopetan elokuvan = I end/stop the movie

Here the movie is the thing that ends, so loppuu is the correct choice.

Because Finnish often leaves out the subject pronoun when the verb ending already shows who the subject is.

• pyyhin = I wipe
• juon = I drink

The ending -n tells you it is first person singular.
You could say minä pyyhin or minä juon, but it usually sounds more emphatic than necessary.

All the verbs here are in the present tense:

• loppuu = ends
• pyyhin = I wipe
• juon = I drink

In Finnish, the present tense is used for several things that English may express in different ways:

• a general/habitual action
• a future event in a time clause
• a simple present statement

So this sentence can feel like:

• When a sad movie ends, I wipe away a tear and drink tea
• or Whenever a sad movie ends, I wipe away a tear and drink tea

Also, Finnish does not have a separate progressive form like I am drinking, so plain present tense covers that idea when needed.

Because Finnish verbs change their stem when they are conjugated.

The dictionary forms are:

• loppua → loppuu
• pyyhkiä → pyyhin
• juoda → juon

So what you see in the sentence is not the infinitive, but the correctly conjugated form.

For example:

• pyyhkiä = to wipe

• pyyhin = I wipe

• juoda = to drink
• juon = I drink

This is very normal in Finnish, so learners often need to get used to recognizing verb stems as well as infinitives.

Because this phrase is the subject of the subordinate clause, so it is in the nominative.

• surullinen = sad
• elokuva = movie

The adjective agrees with the noun in case and number:

• surullinen elokuva = a sad movie

If the noun changed case, the adjective would change too. For example:

• surullista elokuvaa = a sad movie, in the partitive

So the form here is simply the basic subject form.

Because kyyneleen is the form used for a total object in the singular. It has the same shape as the genitive singular.

• kyynel = tear
• kyyneleen = a/the tear, as a complete object

In pyyhin kyyneleen, the idea is that the tear is wiped away as a whole, completed action.

This is why Finnish does not use the basic dictionary form kyynel here.

Also, singular is natural here even if English might sometimes say tears. If you wanted plural, you could say:

• pyyhin kyyneleet = I wipe away the tears

Because teetä is the partitive form, and that is the normal choice when talking about drinking an unspecified amount of a substance.

• tee = tea
• teetä = tea, some tea

So:

• juon teetä = I drink tea / I drink some tea

With drinks and other uncountable substances, Finnish usually uses the partitive unless the amount is clearly limited or otherwise expressed in a special way.

Yes. Finnish word order is fairly flexible, though the original sentence is a very natural neutral order.

For example, you could also say:

Pyyhin kyyneleen ja juon teetä, kun surullinen elokuva loppuu.

That still means basically the same thing, but the emphasis and flow are a little different.

Inside the main clause, you could also reverse the two actions:

Kun surullinen elokuva loppuu, juon teetä ja pyyhin kyyneleen.

So Finnish word order is not as fixed as English word order, but not every order sounds equally natural in every context.

In Finnish, double vowels are pronounced longer, not differently in quality.

So:

• uu in loppuu
• yy in pyyhin
• yy and ee in kyyneleen

must be held longer than a single vowel.

This is important because vowel length can change the meaning of a word in Finnish.

For an English speaker, yy may be especially tricky. It is like a long version of the Finnish y, a front rounded vowel that English does not normally have. The key point is:

• pronounce it clearly
• keep it long
• do not reduce it like an unstressed English vowel

So the spelling in Finnish gives you very useful pronunciation information.