Kesällä kioski myy myös jäätelöä iltaan asti.

Kesällä is the adessive case of kesä (summer), and in time expressions it often means in / during something.

So:

• kesä = summer
• kesällä = in the summer / during the summer

This is a very common Finnish pattern:

• talvella = in winter
• keväällä = in spring
• syksyllä = in autumn

Even though the adessive often has a basic idea of on / at, with seasons and many time expressions it is best learned as a fixed way to say in/during.

Finnish does not have articles like a/an or the.

So kioski can mean:

• a kiosk
• the kiosk

Which one is meant depends on context. In this sentence, English might naturally say the kiosk or a kiosk, but Finnish just uses kioski.

This is normal in Finnish:

• Talo on suuri. = The house is big / A house is big depending on context
• Poika juoksee. = The boy is running / A boy is running

Myydä is the dictionary form (the infinitive), meaning to sell.

In the sentence, the verb must be conjugated to match the subject:

• minä myyn = I sell
• sinä myyt = you sell
• hän / se myy = he/she/it sells
• me myymme = we sell
• te myytte = you (plural) sell
• he ne myyvät = they sell

Here the subject is kioski, which is singular, so the verb is myy.

This is one of the most important questions in Finnish.

Jäätelöä is the partitive singular of jäätelö (ice cream). After many verbs, Finnish often uses the partitive object, especially when the object is:

• uncountable / mass-like
• indefinite
• not presented as a whole completed item/set

Here, sell ice cream is understood as selling some ice cream / ice cream in general, not one complete specifically bounded object. So Finnish uses:

• myy jäätelöä = sells ice cream

Compare:

• Syön jäätelöä. = I am eating ice cream / some ice cream
• Ostan leipää. = I buy bread
• Juon vettä. = I drink water

If the object were a clearly completed whole, another object case might appear.

Yes. The partitive often gives that sense.

In English, we usually just say ice cream, but Finnish jäätelöä can suggest:

• ice cream in general
• some ice cream
• an unspecified amount of ice cream

Because ice cream is a mass noun, the partitive feels natural. It does not necessarily emphasize some strongly every time, but that idea is often in the background.

Myös means also / too / as well.

In this sentence:

• Kesällä kioski myy myös jäätelöä iltaan asti.

it means the kiosk sells ice cream too, in addition to whatever else it sells.

Its position matters a little, because the word near myös is often what is being highlighted.

Here, myös is placed before jäätelöä, so the natural focus is:

• the kiosk sells also ice cream

If you moved it, the emphasis could shift slightly. Finnish word order is flexible, but not random.

Asti means until / up to.

The word before it often appears in a form that shows the endpoint of time or movement. Here:

• ilta = evening
• iltaan = into the evening / until evening
• iltaan asti = until the evening / as late as the evening

So the phrase tells you how long the selling continues.

You can see the same pattern elsewhere:

• aamuun asti = until morning
• yöhön asti = until night
• maanantaihin asti = until Monday

Good question, because both are common time forms.

• illalla = in the evening / during the evening
• iltaan = into the evening / until evening

So:

• illalla tells you when
• iltaan asti tells you how long, up to what point

Compare:

• Kioski on auki illalla. = The kiosk is open in the evening.
• Kioski on auki iltaan asti. = The kiosk is open until the evening.

In your sentence, the idea is an endpoint, so iltaan works with asti.

Yes, Finnish word order is quite flexible compared with English.

Starting with Kesällä puts the time first:

• Kesällä kioski myy myös jäätelöä iltaan asti.

That feels natural if you want to set the scene: In the summer...

Other orders are possible, for example:

• Kioski myy kesällä myös jäätelöä iltaan asti.
• Myös kesällä kioski myy jäätelöä iltaan asti.

These are not all exactly identical in emphasis, but they are grammatical. Finnish often moves words around to control topic and focus, not because the grammar changes.

In standard Finnish, a thing like kioski is grammatically just a noun, and if replaced by a pronoun, it would usually correspond to se (it).

So:

• Kioski myy...
• Se myy... = It sells...

Finnish does not assign grammatical gender like many European languages do. There is no masculine/feminine distinction for nouns.

The form jäätelöä is partitive singular.

For this noun:

• jäätelö = nominative singular
• jäätelöä = partitive singular
• jäätelöt = nominative plural
• jäätelöitä = partitive plural

Because ice cream is often treated as a mass noun, the singular partitive is very common.

If you specifically meant separate ice creams in plural, you might see jäätelöitä instead.

By default, this kind of simple present sentence usually gives a general/habitual meaning.

So kioski myy jäätelöä suggests:

• the kiosk sells ice cream
• it does so as a normal fact or regular activity

With Kesällä, the idea becomes seasonal:

• In the summer, the kiosk also sells ice cream...

So this sounds like a typical summer-time practice, not a one-time event.

A few things:

• ä is not the same as English a. It is a front vowel, somewhat like the vowel in British cat, but keep it pure and short/long as written.
• jäätelöä has long vowels:
  • jää- has ää
  • vowel length matters in Finnish
• myy also has a long vowel sound: yy
• kesällä has doubled ll, so the consonant is held longer than a single l
• iltaan has long aa

In Finnish, both vowel length and consonant length are important and can change meaning, so it helps to pronounce exactly what is written.