Det är förbjudet att cykla över gården, så barnen går där istället.

Here det is a dummy subject. It does not refer to a specific thing like it usually does in English.

Swedish often uses det är + adjective + att-clause in sentences like this:

Det är förbjudet att ... = It is forbidden to ...
Det är viktigt att ... = It is important to ...

So det is just there because Swedish grammar requires a subject in this kind of sentence.

Because förbjudet is the neuter singular form of the adjective.

In this structure, the adjective agrees with det, and det takes the neuter form:

• en förbjuden sak
• ett förbjudet område
• Det är förbjudet att cykla

So even though the real idea is the action att cykla över gården, Swedish still uses the neuter adjective form after det är.

Here att is the infinitive marker, like to in English.

So:

• att cykla = to cycle
• att gå = to walk
• att läsa = to read

In this sentence, att cykla över gården is the action that is forbidden.

Because after att, Swedish uses the infinitive form of the verb.

So:

• cykla = infinitive, to cycle
• cyklar = present tense, cycle / are cycling

Compare:

• Det är förbjudet att cykla över gården. = It is forbidden to cycle across the yard.
• Barnen cyklar över gården. = The children cycle / are cycling across the yard.

In this sentence, över gården means across the yard / across the courtyard, not above it in the air.

This is a very common use of över in Swedish when talking about movement from one side to the other.

So:

• cykla över gården = cycle across the yard
• gå över gatan = walk across the street

A learner might compare:

• på gården = in the yard / on the yard area
• över gården = across the yard
• genom gården = through the yard

Here över suggests movement across that space.

Gården is the definite form of gård.

In this context, gård usually means something like:

• yard
• courtyard
• a shared outdoor area between buildings

So gården means the yard / the courtyard.

The ending -en shows that it is definite:

• en gård = a yard
• gården = the yard

Så here means so, therefore, or as a result.

It connects the two parts of the sentence:

• Det är förbjudet att cykla över gården
• så barnen går där istället

So the logic is:

Cycling across the yard is forbidden, so the children walk there instead.

This is a very common Swedish connector.

Yes, går is the present tense of gå.

• gå = to walk / to go
• går = walk / go / are walking

Swedish often uses the present tense for:

• general facts
• habits
• actions that happen in this situation

So barnen går där istället can mean something like:

• the children walk there instead
• the children go that way instead
• the children are walking there instead

The exact English translation depends on context, but the Swedish present tense works naturally here.

Där usually means there, but here it refers back to the place already mentioned: gården.

So barnen går där istället means that the children walk there instead, meaning they walk across / through that area instead of cycling.

Swedish often uses där to point back to a place that has just been mentioned, even when English might repeat the noun or phrase more directly.

Istället means instead.

It is one word in modern Swedish. You may sometimes also see i stället, which is also accepted in many contexts, but istället is very common.

In this sentence:

barnen går där istället = the children walk there instead

It means they choose walking as an alternative because cycling is not allowed.

That is a natural position for this kind of adverb in Swedish.

Swedish adverbs like istället, också, nog, and similar words can often appear in different places depending on emphasis and sentence structure. In this sentence, putting istället at the end sounds very natural and clearly emphasizes the contrast:

• cycling is forbidden
• walking happens instead

So barnen går där istället is a very normal word order.

Because så here just means so / therefore, not so that.

Compare the difference:

• så = so, therefore, as a result
• så att = so that

In this sentence, the second clause is a result of the first one, so plain så is enough:

Det är förbjudet att cykla över gården, så barnen går där istället.

If you used så att, the meaning would change.

Yes. That would be a very natural alternative.

• Det är förbjudet att ... = It is forbidden to ...
• Det är inte tillåtet att ... = It is not allowed to ...

Both work, but förbjudet sounds a bit stronger and more explicit: it is actually prohibited, not just disallowed.

So your original sentence sounds completely natural and clear.