Min veninde bruger en tung håndvægt, men jeg tager de lettere håndvægte i dag.

Because veninde is a singular en-word (common gender). With a singular en-word, my is min.

Compare:

• min veninde = my female friend
• mit hus = my house
• mine venner = my friends

So the form of my changes depending on the noun’s gender and number.

Yes. Veninde specifically means female friend. Ven means friend, and if gender matters, it is often understood as male friend.

So:

• ven = friend / male friend
• veninde = female friend

That is why min veninde tells you the friend is a woman.

Because håndvægt is a singular en-word, so it takes the indefinite article en.

The adjective tung also matches that pattern. In Danish, an adjective before a singular common-gender noun usually stays in its basic form:

• en tung håndvægt = a heavy dumbbell

If the noun were a singular et-word, you would normally add -t to the adjective:

• et tungt redskab = a heavy piece of equipment

Because Danish usually writes compound nouns as a single word.

Here:

• hånd = hand
• vægt = weight

So håndvægt is literally hand-weight, which is the Danish word for dumbbell.

A useful rule: in Danish compounds, the last part is the main noun. That means vægt determines things like gender and plural form.

They are similar here, but not identical.

• bruger = uses
• tager = literally takes, but in this kind of context it can mean chooses, goes with, or uses for this occasion

So:

• Min veninde bruger en tung håndvægt = My friend uses a heavy dumbbell
• jeg tager de lettere håndvægte i dag = I’m taking/choosing the lighter dumbbells today

In a gym context, tager sounds natural for choosing which weights to work with.

Because de lettere håndvægte means the lighter dumbbells, not just lighter dumbbells in general.

So:

• lettere håndvægte = lighter dumbbells
• de lettere håndvægte = the lighter dumbbells

This suggests a contrast, for example between heavier and lighter dumbbells.

There is also an important grammar pattern here:

• håndvægtene = the dumbbells
• de lettere håndvægte = the lighter dumbbells

When a plural noun is definite and has an adjective before it, Danish uses de.

Because lettere is the comparative form of let.

• let = light
• lettere = lighter

So the sentence is comparing weights: the speaker is choosing the lighter ones.

If you wanted to say simply light dumbbells with no comparison, you would use:

• lette håndvægte

A useful point: comparative adjectives like lettere, større, and mindre do not take extra endings here. So lettere stays lettere.

The singular is en håndvægt, and the plural is håndvægte.

Many Danish nouns form the plural with -e, and some also have a vowel change. Here the base noun vægt becomes vægte, and the compound follows that pattern too:

• en håndvægt
• to håndvægte

Again, the last part of the compound controls the plural form.

Because men is a coordinating conjunction. It joins two main clauses.

That means the second clause keeps normal main-clause word order:

• men jeg tager de lettere håndvægte i dag

Danish main clauses follow the verb-second rule, but here the subject jeg comes first, so the verb naturally comes second:

• jeg tager ...

If you moved i dag to the front, then you would get inversion:

• men i dag tager jeg de lettere håndvægte

I dag is a fixed expression meaning today. Danish does not use an article in that expression.

So:

• i dag = today

Its position at the end is very natural, because time expressions often come later in the sentence:

• jeg tager de lettere håndvægte i dag

But you can also move it to the front for emphasis:

• I dag tager jeg de lettere håndvægte