När ljuset blir grönt, går vi över gatan.

Blir means becomes / turns, while är means is.

So När ljuset blir grönt means When the light turns green.

If you said När ljuset är grönt, that would mean When the light is green. That is also possible Swedish, but it gives a slightly different feel:

• blir grönt = focuses on the change
• är grönt = focuses on the state

In traffic situations, blir grönt is very natural because the light changes color.

Because ljus is a neuter noun in Swedish: ett ljus.

In Swedish, adjectives often change form depending on the gender of the noun. With a singular neuter noun, the adjective usually gets -t.

So:

• ett grönt ljus = a green light
• ljuset blir grönt = the light turns green

Compare:

• en grön bil = a green car
• ett grönt hus = a green house

So grönt agrees with the neuter noun ljuset.

This is a very important Swedish word order rule.

The sentence starts with a subordinate clause:

• När ljuset blir grönt = When the light turns green

After that, the main clause follows, and in Swedish the finite verb comes before the subject if something other than the subject comes first. This is the V2 rule.

So:

• När ljuset blir grönt, går vi över gatan.

Literally, the structure is:

• When the light turns green, go we across the street

That sounds odd in English, but it is normal in Swedish.

Compare:

• Vi går över gatan när ljuset blir grönt.
• När ljuset blir grönt, går vi över gatan.

Both are correct. The second one has inverted word order in the main clause because the sentence begins with När ljuset blir grönt.

Here när means when.

It introduces a time clause:

• När ljuset blir grönt = When the light turns green

This is very common in Swedish.

Examples:

• När jag kommer hem, äter jag. = When I come home, I eat.
• När det regnar, stannar vi inne. = When it rains, we stay inside.

So in your sentence, när connects the event of the light changing with the action of crossing the street.

Literally, ljuset means the light.

In this sentence, though, the context makes it clear that it means the traffic light or the pedestrian signal/light. Swedish often uses ljuset when the situation already makes the meaning obvious.

Formally:

• ljus = light
• ljuset = the light

The ending -et marks the definite form of a neuter noun.

Because Swedish usually puts the definite article at the end of the noun.

So:

• ljus = light
• ljuset = the light

and

• gata = street
• gatan = the street

This is one of the big differences from English.

Compare:

• en gata = a street
• gatan = the street
• ett ljus = a light
• ljuset = the light

So the English word the is often built into the Swedish noun.

Swedish often uses the present tense for things that happen in the future, especially when the timing is clear from context.

So:

• När ljuset blir grönt, går vi över gatan.

uses present tense forms:

• blir
• går

But the meaning is naturally future-oriented: When the light turns green, we will cross the street.

This is very normal in Swedish. English does something similar in time clauses:

• When the light turns green, we cross / will cross the street

You do not normally use a special future form after när here.

It means walk across the street or more generally go across the street.

Word by word:

• går = go / walk
• över = over / across
• gatan = the street

In this context, över is best understood as across.

So gå över gatan is a very common way to say cross the street.

You may also see:

• korsa gatan = cross the street

But gå över gatan is very natural and common in everyday speech.

The comma is possible and helpful, especially because the sentence begins with a subordinate clause.

• När ljuset blir grönt, går vi över gatan.

In modern Swedish, commas are often used less than in English, and in some cases the sentence may also appear without a comma:

• När ljuset blir grönt går vi över gatan.

Both can be acceptable, depending on style. The comma makes the structure easier to see for learners, because it clearly separates the subordinate clause from the main clause.

Yes, absolutely.

That version is also correct:

• Vi går över gatan när ljuset blir grönt.

It means the same thing: We cross the street when the light turns green.

The main difference is emphasis and word order:

• Vi går över gatan när ljuset blir grönt.
  Starts with we cross the street
• När ljuset blir grönt, går vi över gatan.
  Starts with when the light turns green

In the second version, the word order changes to går vi because of the V2 rule.

Yes, the beginning of ljuset can be tricky for English speakers.

lj in Swedish is often pronounced somewhat like a very soft y sound, though the exact pronunciation depends on accent and dialect. So ljuset sounds roughly like YOO-set or LYOO-set to an English speaker, but not exactly.

A rough guide:

• lju- ≈ yu-
• -set = with a short e sound

Also:

• u in Swedish does not sound like English u in blue
• j in Swedish usually sounds like English y

So the word may feel unfamiliar at first, but that is normal.

The Swedish ö does not have an exact match in English.

A rough approximation is the vowel in British English bird, word, or her, but with rounded lips. That is not perfect, but it helps.

So:

• grönt
• över

both contain this ö sound.

For many English speakers, the important thing at first is simply to notice that ö is its own vowel in Swedish and is different from both o and e.

Går is the present tense of gå, which often means go or walk.

In this sentence, it works well because crossing the street is something people physically do on foot. So går vi över gatan is natural.

Depending on context, Swedish can use gå in many places where English might prefer go, walk, or even another verb.

Here it is best understood as:

• we walk/go across the street

So the exact English choice depends on context, but the Swedish is perfectly normal.

It is a subordinate clause, more specifically a time clause.

It gives the time or condition for the action in the main clause:

• När ljuset blir grönt = subordinate clause
• går vi över gatan = main clause

This matters because subordinate clauses and main clauses behave differently in Swedish word order. In particular, once the subordinate clause comes first, the main clause follows the V2 pattern:

• När ljuset blir grönt, går vi över gatan.

Understanding this structure will help you with many Swedish sentences, not just this one.