Vi blander yoghurt i en stor skål, så børnene kan tage lidt selv.

It can mean either one, depending on context.

Danish present tense often covers both:

• we mix
• we are mixing

So Vi blander yoghurt can mean either a general action or something happening right now. Danish does not usually need a separate progressive form like English are mixing.

Because -r is the normal present-tense ending in Danish.

The verb is:

• infinitive: at blande = to mix
• present: blander = mix / am mixing / are mixing

This form stays the same for all persons:

• jeg blander
• du blander
• vi blander

So Danish verbs are much simpler than English in that way.

Because yoghurt is being used as a mass noun, like water, milk, or rice.

When Danish talks about an unspecified amount of a substance, it often uses the noun with no article:

• Vi blander yoghurt = We mix yoghurt / yogurt

If you wanted to make the quantity more explicit, you could say things like:

• noget yoghurt = some yogurt
• yoghurten = the yogurt

You can also say en yoghurt, but then it usually means one yogurt as a container or serving, not yogurt in general.

Because skål is an en-word in Danish, so its indefinite article is en.

Also, the adjective stor is in the correct form for a singular indefinite noun.

Compare:

• en stor skål = a big bowl
• et stort fad = a big dish
• den store skål = the big bowl
• store skåle = big bowls

So:

• en matches the gender of skål
• stor is the right adjective form for that pattern

Because i means in, and a bowl is treated as a container.

So:

• i en stor skål = in a large bowl

That is the natural preposition when something is inside a container. Danish would not normally use på here, because på is more like on a surface.

Here så means so or more exactly so that.

It introduces the purpose or result of the first clause:

• Vi blander yoghurt i en stor skål, så børnene kan tage lidt selv.
• We mix yogurt in a large bowl so that the children can take some themselves.

This is different from other uses of så, which can also mean things like:

• then
• so
• thus depending on context.

Because the sentence is divided into two clauses, and the comma marks that boundary.

The first clause is:

• Vi blander yoghurt i en stor skål

The second clause is:

• så børnene kan tage lidt selv

In Danish, many writers put a comma before a subordinate clause like this. That is very common and fully standard in the comma system that uses start comma. You may also see sentences without that comma in other writing styles, but this version is very normal.

Because barn has an irregular plural.

The forms are:

• et barn = a child
• barnet = the child
• børn = children
• børnene = the children

So the plural is not built regularly from barn. The vowel changes:

• barn → børn

Then the definite plural ending -ene is added:

• børn
  • -ene = børnene

Because kan is a modal verb, and modal verbs in Danish are followed by a bare infinitive.

So:

• kan tage = can take

Not:

• kan at tage

This is similar to English:

• can take not
• can to take

Other Danish modal verbs work the same way:

• vil tage = want to take / will take
• skal tage = must / is going to take
• må tage = may / is allowed to take

Because så here is a conjunction meaning so that, and it introduces a subordinate clause.

In that kind of clause, Danish does not use the main-clause inversion pattern. So the normal order is:

• børnene kan tage

If you said:

• så kan børnene tage lidt selv

that would usually sound more like a new main clause:

• then the children can take some themselves or
• so the children can take some themselves

So the version in your sentence shows that så is linking the clauses in a subordinating way.

Here lidt means a little or some.

So:

• tage lidt = take a little / take some

It refers to a small, unspecified amount. With food, this is very natural Danish.

It does not have to mean a tiny amount in a strict sense; often it is just a polite, everyday way to talk about taking some food.

Selv adds the idea of themselves, on their own, or by themselves.

So:

• børnene kan tage lidt selv

means that the children can serve themselves, instead of an adult doing it for them.

Placing selv at the end is very natural here. It gives emphasis to the idea that they do it independently.