Hon tar rulltrappan ner till tunneln under stationen.

Yes, tar is the present tense of ta, which often literally means take. But in Swedish, ta is also very commonly used for choosing or using a means of getting somewhere.

So:

• ta bussen = take the bus
• ta hissen = take the elevator
• ta trappan = take the stairs
• ta rulltrappan = take the escalator

So Hon tar rulltrappan is the natural way to say She takes the escalator.

Swedish very often makes compounds by joining words together into a single word.

Here:

• rull relates to rolling
• trappa = stairs

So rulltrappa = escalator

This is very normal in Swedish. English sometimes writes similar ideas as two words, but Swedish usually prefers one compound word.

Other examples:

• sjukhus = hospital
• järnvägsstation = railway station
• sommarhus = summer house

Because Swedish usually puts the definite article on the end of the noun instead of using a separate word like the.

So:

• en rulltrappa = an escalator

• rulltrappan = the escalator

• en tunnel = a tunnel

• tunneln = the tunnel

• en station = a station
• stationen = the station

This is one of the biggest differences from English. Instead of the escalator, Swedish says escalator-the.

The sentence is talking about specific, identifiable places:

• rulltrappan = the escalator
• tunneln = the tunnel
• stationen = the station

That sounds natural because the speaker has a particular escalator, tunnel, and station in mind.

If you used indefinite forms, the meaning would become more general or less specific:

• Hon tar en rulltrappa... = She takes an escalator...
• ...till en tunnel... = ...to a tunnel...
• ...under en station = ...under a station

That would sound much less natural in most normal contexts.

Ner means down.

It adds the idea of downward movement:

• Hon tar rulltrappan = She takes the escalator
• Hon tar rulltrappan ner = She takes the escalator down

In this sentence, ner tells you the direction of travel: she is going downward.

Because the sentence expresses both:

1. direction: ner = down
2. destination: till tunneln = to the tunnel

So:

• ner = down
• till = to
• ner till tunneln = down to the tunnel

English does the same thing: down to the tunnel.

Because till marks the destination or endpoint of movement.

• till tunneln = to the tunnel
• i tunneln = in the tunnel
• på tunneln = on the tunnel

Here she is moving toward the tunnel, not already inside it. So till is the right choice.

It most naturally describes tunneln.

So the structure is:

• tunneln under stationen = the tunnel under the station

In other words, it means the tunnel that is under the station.

That is the most natural reading of the sentence.

Because rulltrappan is the object of tar, and in this kind of sentence Swedish naturally puts the object before the directional word.

So:

• Hon tar rulltrappan ner till tunneln.

This is the normal word order.

A rough pattern is:

subject + verb + object + direction + destination

So:

• Hon
  • tar
    • rulltrappan
      • ner
        • till tunneln

English learners sometimes expect ner to come earlier, but this Swedish order is very natural.

Yes. Ner and ned are closely related, and in many contexts both are possible.

So you may also see:

• Hon tar rulltrappan ned till tunneln under stationen.

In modern everyday Swedish, ner is very common in speech and informal writing. Ned can feel a bit more formal or written, depending on context.

Yes, but the meaning changes.

• Hon tar rulltrappan ner till tunneln under stationen = She takes the escalator down to the tunnel under the station.
• Hon går ner till tunneln under stationen = She goes/walks down to the tunnel under the station.

The second sentence does not mention the escalator at all. It just says she goes down there.

So tar rulltrappan is important if you want to specify how she gets down.