Paraplyen er praktisk, når det regner.

Paraplyen means the umbrella, while paraply means umbrella.

In Danish, the definite article is often added to the end of the noun instead of being a separate word in front:

• en paraply = an umbrella
• paraplyen = the umbrella

So Paraplyen er praktisk means The umbrella is practical.

Because paraply is a common gender noun in Danish, so its indefinite article is en:

• en paraply = an umbrella

Common gender nouns usually take -en in the definite singular:

• paraplyen = the umbrella

If it were a neuter noun, it would use et and typically -et in the definite form.

Here praktisk is a predicate adjective, meaning it comes after er and describes the subject.

In this sentence:

• Paraplyen er praktisk = The umbrella is practical

When an adjective is used this way in Danish, it often appears in its basic form. You do not add -t here, because paraplyen is a common gender noun, not a neuter noun.

Compare:

• En paraply er praktisk = An umbrella is practical
• Et værktøj er praktisk = A tool is practical

So yes, adjective form depends partly on gender and use, and here praktisk is the correct form.

In this sentence, når means when in the sense of whenever or at times when:

• Paraplyen er praktisk, når det regner.
• The umbrella is practical when it rains.

A very common difference is:

• når = when/whenever for repeated or general situations, and often for the future
• da = when for a specific event in the past

Examples:

• Når det regner, tager jeg en paraply.
  When/Whenever it rains, I take an umbrella.
• Da det regnede i går, tog jeg en paraply.
  When it rained yesterday, I took an umbrella.

So når is the right choice here because the sentence expresses a general truth.

Det here is a dummy subject, just like it in English weather expressions.

So:

• det regner = it rains / it is raining

The det does not refer to a specific thing. It is simply required by the grammar.

Other weather examples:

• Det sner = It is snowing
• Det blæser = It is windy / It’s blowing

So this works very much like English it in it rains.

Yes. Regner is the present tense of at regne.

In Danish, the present tense often covers both:

• it rains
• it is raining

So når det regner can mean:

• when it rains
• when it is raining

The exact meaning depends on context. In this sentence, it is most naturally understood as a general statement: when it rains.

Because Danish normally uses a comma before a subordinate clause.

Here:

• Paraplyen er praktisk = main clause
• når det regner = subordinate clause

So the comma is standard Danish punctuation:

• Paraplyen er praktisk, når det regner.

This is more regular in Danish than in English, where the comma is often omitted in similar sentences.

Yes, absolutely. That word order is correct too:

• Når det regner, er paraplyen praktisk.

It means the same thing, but the emphasis is slightly different. Starting with Når det regner puts the condition first: When it rains...

Also notice the word order in the main clause after the subordinate clause:

• Når det regner, er paraplyen praktisk.

The verb er comes before the subject paraplyen. This is a normal Danish word order rule when something else comes first in the sentence.

Yes. Praktisk often overlaps with English words like:

• practical
• useful
• handy
• sometimes convenient, depending on context

In this sentence, practical is the most direct translation, but the idea is that an umbrella is useful/handy when it rains.

A simple learner-friendly pronunciation guide would be something like:

• paraplyen ≈ pa-ra-PLOO-en

A few helpful notes:

• The stress is mainly on ply
• The final -en is the definite ending
• The y sound in Danish is not exactly like English oo, but that approximation can help at first

If you want to say the full sentence naturally, the rhythm is roughly:

• pa-ra-PLOO-en er prak-TISK, nor deh RAIN-er

That is only an approximation, but it may help you get started.

Grammatically, paraplyen means the umbrella, so it can refer to a specific umbrella.

But in real usage, Danish sometimes uses the definite form in ways that sound more general than English learners expect. Depending on context, the sentence can be understood as:

• The umbrella is practical when it rains
  or more generally:
• An umbrella is practical when it rains

If you wanted a clearly general statement, you could also say:

• En paraply er praktisk, når det regner.
  An umbrella is practical when it rains.

So context matters.

The dictionary forms are:

• paraply = umbrella
• være = to be
• praktisk = practical
• når = when
• det = it
• regne = to rain

In the sentence, some of them appear in changed forms:

• paraplyen = definite singular of paraply
• er = present tense of være
• regner = present tense of regne