Vi har en reservation til fredag, men min veninde vil hellere komme på lørdag.

Because reservation is a common-gender noun in Danish, so it takes en.

• en reservation = a reservation
• definite form: reservationen = the reservation

In Danish, nouns are either common gender (en-words) or neuter (et-words), and this has to be memorized with each noun.

This is a very common learner question.

In this sentence:

• til fredag means for Friday
• på lørdag means on Saturday

So the two prepositions are doing slightly different jobs:

• en reservation til fredag = a reservation for Friday
• komme på lørdag = come on Saturday

With bookings, appointments, and reservations, Danish often uses til where English uses for.
With days when something happens, Danish often uses på where English uses on.

So:

• Vi har en reservation til fredag = We have a reservation for Friday
• Hun kommer på lørdag = She is coming on Saturday

Because in Danish, days of the week usually appear without an article.

So you say:

• fredag = Friday
• lørdag = Saturday

Not:

• en fredag
• en lørdag

unless you mean something like a Friday in a more general sense.

In this sentence, the days are just being used as calendar days, so no article is needed.

Veninde means female friend.
Ven means friend, often understood as a male friend, though context can matter.

So:

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

The ending -inde is a feminine ending found in some Danish words.

Because possessives like min, din, hans, hendes, vores, etc. normally replace the indefinite article.

So Danish uses:

• min veninde = my friend

not:

• en min veninde

This is the same basic idea as in English: we say my friend, not a my friend.

Hellere means rather or would rather.

In the sentence:

• min veninde vil hellere komme på lørdag

it means:

• my friend would rather come on Saturday

So hellere expresses preference between alternatives.

A useful comparison:

• Jeg vil komme fredag. = I want to come Friday.
• Jeg vil hellere komme lørdag. = I would rather come Saturday.

In Danish, adverbs like hellere often come after the finite verb and before the main infinitive.

Here:

• vil = finite verb
• hellere = adverb
• komme = infinitive

So the pattern is:

• vil hellere komme

This is very natural Danish word order.

Compare:

• Jeg vil gerne komme. = I would like to come.
• Jeg vil hellere komme senere. = I would rather come later.

Because komme is very commonly used in Danish for going/coming to an event, place, or appointment.

So:

• komme på lørdag = come on Saturday

sounds natural in this context.

You could use verbs related to arrival in other situations, but komme is the ordinary, idiomatic choice here.

Literally, it means We have a reservation.

But in real usage, it often implies that a booking already exists, so in context it can feel close to:

• We’ve booked for Friday
• We have a booking for Friday

Danish often uses have in exactly this natural way.

Because men means but, and it introduces a new main clause.
After men, Danish usually keeps main clause word order, which means the subject comes before the verb if nothing else has been moved to the front.

So:

• men min veninde vil hellere komme på lørdag

has:

• min veninde = subject
• vil = finite verb

This is normal main-clause order.

Not here.

In this sentence, til fredag clearly means for Friday, because it goes with reservation:

• en reservation til fredag = a reservation for Friday

Danish til can have many meanings, including to, for, and sometimes something close to until depending on context. But here the meaning is definitely connected to the date of the reservation.

Because the two phrases have different structures:

• en reservation til fredag
  Here fredag is part of a phrase describing the reservation: for Friday.

• komme på lørdag
  Here på lørdag is a time expression linked to the verb komme: come on Saturday.

So the difference is not really about the position of the day itself, but about what kind of phrase it belongs to.

Mostly yes. Reservation in Danish is very similar to English reservation, especially for restaurants, hotels, tickets, and similar bookings.

For example:

• Vi har en reservation. = We have a reservation.
• Jeg vil gerne lave en reservation. = I would like to make a reservation.

In some situations, Danish speakers may also use other words like booking, especially in modern everyday language, but reservation is perfectly normal and correct.

Then you would usually say:

• Vi har en reservation til fredag, men min ven vil hellere komme på lørdag.

The only change is:

• min veninde → min ven

Everything else stays the same.