Barnen väntar alltid vid övergångsstället tills ljuset blir grönt.

Barn is a slightly unusual noun in Swedish:

• ett barn = a child
• barn = children (indefinite plural)
• barnet = the child
• barnen = the children

So barnen is the definite plural form, meaning the children.

Väntar is the present tense of vänta = to wait.

So:

• vänta = to wait
• väntar = wait / is waiting / are waiting

In Swedish, the present tense often covers both simple present and present continuous meanings that English separates:

• Barnen väntar can mean The children wait or The children are waiting, depending on context.

Because the sentence also has alltid = always, the habitual meaning is most natural: The children always wait...

In a normal Swedish main clause, the finite verb usually comes early, and sentence adverbs like alltid, ofta, inte, and aldrig usually come after that verb.

So:

• Barnen väntar alltid...

This is different from English, where always often comes before the main verb:

• The children always wait...

This is a very common Swedish pattern.

Here, vid means at, by, or next to.

So:

• vid övergångsstället = at the pedestrian crossing / by the crosswalk

Vid is used for being located near a specific place or point.

Using på would sound less natural here. På often means on or at in other contexts, but with övergångsställe, Swedish normally uses vid when talking about waiting near it.

Swedish often builds long compound nouns by joining smaller words together.

Övergångsstället comes from:

• övergång = crossing / passage
• ställe = place / spot
• övergångsställe = pedestrian crossing / crosswalk
• övergångsstället = the pedestrian crossing / the crosswalk

So the final -t makes it definite singular.

This is very normal in Swedish. English often writes these as separate words, while Swedish frequently joins them.

Because the sentence means the pedestrian crossing, not just a pedestrian crossing.

• ett övergångsställe = a pedestrian crossing
• övergångsstället = the pedestrian crossing

The noun övergångsställe is a neuter noun (an ett noun), so its definite singular form gets -t.

Tills means until.

It introduces the point in time when something changes:

• Barnen väntar ... tills ljuset blir grönt
• The children wait ... until the light turns green

So the waiting continues up to that moment.

A very common learner mistake is confusing tills with innan:

• tills = until
• innan = before

They are not interchangeable here.

Yes. Ljuset is the definite form of ljus:

• ett ljus = a light
• ljuset = the light

In this sentence, it refers to the traffic signal light, not light in a general abstract sense.

So ljuset blir grönt means the light turns green.

Because blir means becomes or turns.

• är grönt = is green
• blir grönt = becomes green / turns green

At a crossing, the light changes color. The sentence is talking about that change, so blir is the natural choice.

Because grönt agrees with ljuset, which is a neuter noun.

The adjective grön changes form depending on what it describes:

• en grön bil = a green car
• ett grönt ljus = a green light
• gröna bilar = green cars

Here we have ljuset, and ljus is an ett noun, so the adjective must be grönt.

This agreement also happens after verbs like är and blir:

• Ljuset är grönt
• Ljuset blir grönt

Yes. Tills introduces a subordinate clause.

The clause is:

• tills ljuset blir grönt

Here the order is:

• tills
  • subject + verb + adjective

That is normal Swedish subordinate-clause structure.

A useful thing to notice is that Swedish does not do English-style extra helping verbs here. It simply says:

• ljuset blir grönt = the light turns green

Very direct and compact.

Grammatically, Swedish present tense can cover that kind of meaning, but in this sentence the most natural interpretation is habitual:

• The children always wait at the crossing until the light turns green

Because of alltid, it sounds like a repeated behavior or rule, not one ongoing scene.

If Swedish wanted to strongly emphasize an ongoing action right now, it would usually rely on context or add another expression rather than changing the tense.