Hun sætter en vægtskive på stangen, før hun begynder sin styrketræning.

Sætter is the natural choice here because sætte means to put / place / set something into position.

Danish often distinguishes between placement verbs more than English does:

• sætte = set/put something into place
• lægge = lay something down
• stille = stand/put something upright

With a weight plate being put onto a bar, sætte ... på sounds idiomatic. Lægge would sound less natural here.

Vægtskive is a compound noun:

• vægt = weight
• skive = disc / plate

So vægtskive literally means weight-disc, which corresponds to weight plate in gym English.

Danish makes compound nouns very freely, so it is normal to see long words like this written as one word.

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

So:

• en stang = a bar
• stangen = the bar

Here stang is an en-word (common gender), so the definite singular ending is -en.

Because the sentence is talking about a specific bar, not just any bar.

• på en stang = on a bar / onto a bar
• på stangen = on the bar / onto the bar

In context, it is understood which bar is meant, so the definite form is natural.

Here it has the sense of onto even though the Danish word is still på.

Danish often uses the same preposition where English distinguishes between:

• on = location
• onto = movement toward a surface/object

So sætter en vægtskive på stangen means she is moving the plate onto the bar, even though Danish just says på.

Because før introduces a subordinate clause.

In Danish, subordinate clauses normally keep the order:

• subject + verb

So:

• før hun begynder = before she begins

The verb-second rule belongs to main clauses, not subordinate clauses.

A useful comparison:

• Hun sætter ... før hun begynder ...
• Før hun begynder ..., sætter hun ...

In the second sentence, the main clause comes after the subordinate clause, so you get inversion: sætter hun.

Because sin is the reflexive possessive used when the possessor is the same as the subject of the clause.

Here the subject is hun, and the training belongs to that same person, so Danish uses sin:

• hun ... sin styrketræning = she ... her own strength training

If you used hendes, it would usually suggest someone else’s training, not the subject’s.

Also, the form sin is used because styrketræning is singular and common gender. The related forms are:

• sin = common singular
• sit = neuter singular
• sine = plural

Because the sentence is describing a general action or routine, and Danish often uses the present tense for that.

Also, after a time word like før, Danish normally still uses the present when talking about a regular sequence:

• før hun begynder = before she begins

This is actually similar to English, which also says before she begins, not before she will begin.

If the whole sentence were in the past, you would get:

• Hun satte ... før hun begyndte ...

Because Danish normally writes compound nouns as one word.

Styrketræning is built from:

• styrke = strength
• træning = training

Together they form one concept, so they become one written word: styrketræning.

You will see this all the time in Danish. What English often writes as two words, Danish often writes as one.

The comma is very common and fully correct here because før hun begynder sin styrketræning is a subordinate clause.

In Danish, there are two accepted comma styles:

• a style that uses a comma before subordinate clauses
• a newer style that often omits that comma

So both of these may be seen:

• Hun sætter en vægtskive på stangen, før hun begynder sin styrketræning.
• Hun sætter en vægtskive på stangen før hun begynder sin styrketræning.

The version with the comma is especially common in teaching materials.

A few parts are especially difficult for English speakers:

• sætter: the æ sounds somewhat like the vowel in cat, but usually a bit more open
• før: the ø has no exact English equivalent; it is similar to the vowel in French peur or German schön (depending on accent)
• styrke: the y is also unfamiliar to English speakers; it is like saying ee while rounding your lips
• træning: again, watch the æ

You do not need perfect pronunciation immediately, but y, ø, and æ are worth practicing early because they are very common in Danish.