En rolig tur i haven gør hverdagen lettere.

Because tur is a common-gender noun in Danish, and common-gender nouns take en.

• en tur = a walk / a trip
• et is used with neuter nouns

So the noun decides the article:

• en rolig tur
• but, for example, et roligt sted if sted is neuter

A good habit is to learn Danish nouns together with their article:

• en tur
• en have
• en hverdag

Because the adjective has to match the noun phrase.

Here, tur is:

• singular
• indefinite
• common gender

So the adjective stays in its basic form:

• en rolig tur

Compare:

• et roligt sted = neuter singular indefinite
• rolige ture = plural
• den rolige tur = definite

So in this sentence, rolig is the correct form because it describes en tur.

Tur is a very common Danish word with a few related meanings, depending on context. Here it means something like:

• walk
• stroll
• trip
• outing

In En rolig tur i haven, the most natural sense is probably a calm/peaceful walk in the garden.

So tur is broader than just one English word. Danish often uses tur where English might choose walk, trip, or go for a stroll.

Because haven is the definite singular form of have.

• have = garden
• haven = the garden

So:

• i have would not be correct here
• i haven = in the garden

This is a very common Danish pattern:

• en have → haven
• en dag → dagen
• en bil → bilen

In Danish, the definite article is usually added to the end of the noun instead of being a separate word like English the.

Because Danish often forms compound nouns by joining words together.

Here:

• hverdag = everyday life / weekday / daily life, depending on context
• hver
  • dag originally combine into one word

Then the definite ending is added:

• hverdag = everyday life / weekday
• hverdagen = everyday life / the everyday routine

English often writes similar ideas as two words, but Danish very often prefers one compound word.

Because the sentence is talking about everyday life in a general, familiar sense: the everyday routine / day-to-day life.

• hverdag can mean an everyday life / a weekday / everyday routine in a more general or dictionary-like sense
• hverdagen often means everyday life as something concrete and recognizable

So:

• gør hverdagen lettere = makes everyday life easier

This definite form is very natural in Danish with broad, familiar concepts like:

• livet = life
• hverdagen = everyday life
• arbejdet = work

English often uses no article where Danish prefers the definite form.

It comes from the verb gøre, which often means to do, but in this sentence it means to make.

So:

• gør hverdagen lettere = makes everyday life easier

This is very common in Danish:

• Det gør mig glad. = It makes me happy.
• Motion gør kroppen stærkere. = Exercise makes the body stronger.

So yes, gøre can mean do, but in this kind of structure it often means make.

The subject does come first here, but the whole phrase En rolig tur i haven is the subject.

So the structure is:

• En rolig tur i haven = subject
• gør = verb
• hverdagen lettere = object/complement

Danish main clauses usually follow the V2 rule, meaning the finite verb is in the second position.

Here, the first position is occupied by the entire subject phrase: En rolig tur i haven Then the verb comes: gør

So the word order is completely normal Danish.

Here lettere is the comparative form of the adjective let.

• let = easy / light
• lettere = easier / lighter

In this sentence it means easier:

• gør hverdagen lettere = makes everyday life easier

It is functioning as a complement describing hverdagen, not as an adverb.

Compare:

• en let opgave = an easy task
• opgaven er lettere nu = the task is easier now

Because let is a short adjective, and short adjectives in Danish usually form the comparative with -ere.

• let → lettere
• stor → større
• rolig → roligere

Using mere + adjective is possible in some cases, especially with longer adjectives, but with let, lettere is the normal and natural form.

So:

• hverdagen bliver lettere = natural
• hverdagen bliver mere let = not natural here

Yes, rolig can cover several English words depending on context:

• calm
• quiet
• peaceful
• sometimes relaxed

In En rolig tur i haven, the most natural English choices are probably:

• a peaceful walk in the garden
• a calm walk in the garden
• a quiet stroll in the garden

So the exact English word depends on style and context, but the Danish idea is that the walk is gentle, restful, and not hectic.

Yes, grammatically you could, but it changes the meaning slightly.

• i haven = in the garden
  This sounds like a specific, known garden
• i en have = in a garden
  This sounds more general or indefinite

In your original sentence, i haven feels more natural because it suggests a familiar setting, like your garden or the garden around you.

So both are possible, but i haven is the more natural choice in this sentence.