Jeg viser mit rejsekort, før jeg stiger på metroen.

Because rejsekort is a neuter noun in Danish.

Danish indefinite articles:

• en for common gender nouns
• et for neuter nouns

Kort is a neuter noun, so words that agree with it also take neuter forms:

• et kort
• mit kort

Since rejsekort ends with -kort, and the whole compound noun takes its gender from the last part, it is:

• et rejsekort
• mit rejsekort

So mit rejsekort means my travel card.

Rejsekort is a compound noun made from:

• rejse = travel/journey
• kort = card

So literally it means travel card.

In Denmark, Rejsekort is also the name of the electronic public transport card used for buses, trains, and the metro. In many contexts, it refers specifically to that system, not just any random travel card.

Because Danish, like German, commonly forms compound nouns by writing them as a single word.

So instead of writing:

• rejse kort

Danish writes:

• rejsekort

This is very normal in Danish. A few more examples:

• togstation = train station
• busbillet = bus ticket
• cykelhjelm = bicycle helmet

English often uses spaces where Danish prefers one combined word.

Viser is the present tense of at vise, which means to show.

So:

• jeg viser = I show / I am showing

In this sentence, it means something like I show my travel card.

Depending on context, English might say:

• I show my travel card
• I present my travel card

At stige på is an expression meaning to get on, to board, or literally to step onto a form of transport.

So:

• jeg stiger på metroen = I get on the metro

The verb is:

• stige = step/rise
• stige på = get on / board

This is a very common transport expression in Danish.

Related expressions:

• stige på bussen = get on the bus
• stige på toget = get on the train
• stige af metroen = get off the metro

Because with the verb stige på, Danish uses på.

This is a fixed expression:

• stige på bussen
• stige på toget
• stige på metroen

Even though English says get on the metro, learners sometimes expect i because they are physically inside it. But Danish follows the verb phrase stige på, so på is the normal choice when talking about boarding.

After you are already inside, Danish may use i in other contexts:

• Jeg sidder i metroen = I’m sitting in the metro

So:

• stige på metroen = board the metro
• være i metroen = be in the metro

Because metroen is the definite form of metro.

In Danish, the definite article is usually added to the end of the noun:

• en metro = a metro
• metroen = the metro

So på metroen means on the metro or onto the metro, depending on context.

This is different from English, which uses a separate word:

• the metro

Danish often attaches definiteness directly to the noun.

Because før jeg stiger på metroen is a subordinate clause.

In Danish subordinate clauses, the word order is usually more like English:

• før jeg stiger på metroen
• because I get on the metro
• when I arrive

The subject comes before the verb:

• jeg stiger

You do not use the normal main-clause inversion here.

Compare:

Main clause:

• Jeg stiger på metroen.

Subordinate clause:

• før jeg stiger på metroen

So after før meaning before, Danish keeps the subject-verb order jeg stiger.

Because før jeg stiger på metroen is a full clause with its own subject and verb.

The sentence has two clauses:

1. Jeg viser mit rejsekort
2. før jeg stiger på metroen

Each clause needs its own subject, so jeg appears in both places.

English works the same way:

• I show my travel card before I get on the metro.

You would not normally say:

• before get on the metro

You need I there too.

Because Danish often uses the present tense for:

• habitual actions
• general statements
• near-future actions
• instructions or descriptions of routine

So:

• Jeg viser mit rejsekort, før jeg stiger på metroen

can describe a usual action:

• I show my travel card before I get on the metro

This sounds natural in both Danish and English when talking about routine or sequence.

If the sentence is about a general habit, present tense is exactly what you would expect.

Not always. It depends on the Danish comma system being used.

The sentence has:

• Jeg viser mit rejsekort, før jeg stiger på metroen.

That comma is common in the traditional system, where a comma is often placed before subordinate clauses.

In new comma style, many writers would leave it out:

• Jeg viser mit rejsekort før jeg stiger på metroen.

So the version with the comma is not wrong, but you may also see the sentence without it.

Yes. If the subordinate clause comes first, the main clause follows normal Danish V2 word order, meaning the finite verb comes before the subject.

So:

• Jeg viser mit rejsekort, før jeg stiger på metroen.

can also become:

• Før jeg stiger på metroen, viser jeg mit rejsekort.

Notice the change:

• jeg viser → viser jeg

That happens because the clause Før jeg stiger på metroen takes the first position, so the verb in the main clause must come next.

Yes, it is natural, but there are other possibilities depending on context.

Possible alternatives include:

• Jeg viser mit rejsekort = I show my travel card
• Jeg scanner mit rejsekort = I scan my travel card
• Jeg tjekker ind med mit rejsekort = I check in with my travel card

The best choice depends on what is actually happening:

• If you literally present it to a person or machine, viser works well.
• If you tap it on a reader, scanner or tjekker ind may be more specific.

So the sentence is grammatically natural, but real-life usage may vary with context.