Barnen fick varsin glass efter lunch, eftersom det var så varmt.

Barnen is the definite plural form: the children.

A few useful forms are:

• ett barn = a child
• barn = children / child in some contexts
• barnen = the children

So the sentence is talking about a specific group of children, not just children in general.

One thing that often surprises English speakers is that barn is an ett-word, and its plural indefinite form is also barn.

Fick is the past tense of få.

• få = to get, to receive, sometimes to be allowed to have
• fick = got

So barnen fick ... means the children got ...

In this sentence, fick sounds natural as received/were given:

• Barnen fick varsin glass = The children got an ice cream each

Varsin means one each or one apiece.

It is used when several people/things each get one of something.

So:

• Barnen fick varsin glass = The children got an ice cream each

This word is very common in Swedish and is often more natural than trying to say each got one in a longer way.

It also changes form depending on the noun:

• varsin
  • en-word
    • varsin glass
• varsitt
  • ett-word
    • varsitt äpple
• var sina
  • plural noun
    • var sina böcker = their own books, one set each

Because varsin already functions like a determiner, so you do not add en or ett.

Compare:

• en glass = an ice cream
• varsin glass = an ice cream each

So varsin replaces the article here.

This is similar to how in English you would not normally say each an ice cream a. The determiner slot is already filled.

Yes. In Swedish, glass commonly means ice cream.

Examples:

• Jag vill ha glass. = I want ice cream.
• en glass = an ice cream / an ice cream treat

So in this sentence, glass is not talking about the material glass. Context makes it clear that it means ice cream.

Swedish often leaves out the article with meals and other routine time expressions.

So you commonly say:

• efter lunch = after lunch
• före middag = before dinner
• efter frukost = after breakfast

If you say efter lunchen, that usually means after the lunch in a more specific sense, referring to a particular lunch already identified in the conversation.

So efter lunch is the most natural general phrasing here.

Eftersom means because or since.

In this sentence:

• eftersom det var så varmt = because it was so warm

For learners, an important point is that eftersom introduces a subordinate clause.

It is often more clearly causal than för att, which can sometimes mean in order to as well as because, depending on context.

Examples:

• Jag gick hem eftersom jag var trött. = I went home because I was tired.

• Jag gick hem för att sova. = I went home in order to sleep.

So eftersom is a very clear choice when you want to say because.

In Swedish, weather and general conditions often use a dummy subject: det.

So you say:

• Det är varmt. = It is warm.
• Det var kallt. = It was cold.

This is very similar to English it in it is hot.

So det does not refer to a specific thing here. It is just the normal grammatical subject used for weather or general conditions.

Because the adjective is agreeing with det, which takes the neuter form.

Adjective forms:

• varm = common gender singular
• varmt = neuter singular / adverb-like use
• varma = plural / definite

Since the phrase is det var ..., Swedish uses:

• det var varmt

Compare:

• Soppan var varm. = The soup was warm.
• Vädret var varmt. = The weather was warm.
• Det var varmt. = It was warm.

Because eftersom introduces a subordinate clause, and in Swedish subordinate clauses do not follow the usual main-clause V2 pattern.

Main clause:

• Det var så varmt.

Subordinate clause after eftersom:

• eftersom det var så varmt

So the subject det stays before the verb var.

This is a very important Swedish pattern:

• main clause: verb usually comes second
• subordinate clause: subject usually comes before the verb

You can also see the contrast if the eftersom clause comes first:

• Eftersom det var så varmt, fick barnen varsin glass efter lunch.

Here the main clause after the comma has inversion:

• fick barnen not
• barnen fick

Yes, literally it is so warm, but in natural English it often corresponds to so warm, very warm, or such a warm day/condition, depending on context.

In Swedish, så often expresses degree:

• så varmt = so warm
• så kallt = so cold
• så roligt = so fun

Here it implies that the warmth was the reason for giving the children ice cream.

So it is not just a neutral temperature description; it suggests warm enough that it made sense to give them ice cream.