Hvis jeg ikke får svar på ansøgningen i denne uge, vil jeg sende en venlig besked på mandag.

Because in a Danish subordinate clause introduced by hvis, the normal word order is:

subject + sentence adverb + finite verb

So:

• jeg = subject
• ikke = sentence adverb
• får = finite verb

That gives jeg ikke får.

This is different from a normal main clause, where the finite verb usually comes earlier. Compare:

• Jeg får ikke svar. = main clause
• Hvis jeg ikke får svar ... = subordinate clause

This word order is very common in Danish.

Danish often uses the present tense in an if-clause when the meaning is future, just like English does.

Compare:

• English: If I don't get a reply this week, I will send...
• Danish: Hvis jeg ikke får svar i denne uge, vil jeg sende...

So får is present tense, but the whole clause still refers to a possible future situation.

The same thing happens in English:

• If it rains tomorrow, we'll stay home.

You do not normally use vil inside this kind of hvis clause.

This is because Danish is a V2 language in main clauses. That means the finite verb normally comes in the second position.

Here, the sentence begins with the whole hvis-clause:

Hvis jeg ikke får svar på ansøgningen i denne uge, ...

After that, the main clause begins, and the finite verb must come before the subject:

• vil = finite verb
• jeg = subject

So you get:

..., vil jeg sende en venlig besked på mandag.

If the sentence started directly with the main clause, it would be:

• Jeg vil sende en venlig besked på mandag.

But after a fronted clause, Danish changes the order to verb + subject.

At få svar means to get a reply / to receive an answer.

So:

• jeg får svar = I get a reply
• jeg ikke får svar = I do not get a reply

This is a very common Danish expression. Danish often uses få + noun in places where English might use receive or get.

For example:

• få hjælp = get help
• få besked = get a message / be informed
• få svar = get a reply

In Danish, svar på is a fixed pattern meaning reply to or answer to something.

So:

• svar på ansøgningen = a reply to the application

English speakers sometimes expect something more direct, but Danish often uses a preposition here.

Other similar examples:

• et svar på mit spørgsmål = an answer to my question
• svar på e-mailen = a reply to the email

So på belongs naturally with svar in this kind of expression.

Ansøgningen is the definite form: the application.

The ending -en is attached to the noun because ansøgning is a common-gender noun:

• en ansøgning = an application
• ansøgningen = the application

The definite form is used because the speaker is talking about a specific application that both speaker and listener can identify.

So in context, it means:

the application I already sent / the application we both know about

Yes, Danish can often say both i denne uge and denne uge, but i denne uge makes the time expression a bit more explicit as during this week.

So:

• i denne uge = in/during this week
• denne uge = this week

In many contexts, both are natural. The version with i is especially common when emphasizing the time period.

Also note:

• denne means this
• uge means week

So denne uge = this week.

In Danish, days are commonly used with på when you mean on Monday, on Tuesday, etc.

So:

• på mandag = on Monday
• på tirsdag = on Tuesday
• på fredag = on Friday

That is the normal preposition here.

Depending on context, på mandag can often mean this coming Monday / next Monday.

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

• en besked = a message
• beskeden = the message

So:

• en venlig besked = a friendly message

You simply have to learn the gender of each noun, because Danish nouns are either:

• common gender: en
• neuter: et

Here, venlig matches en besked.

Yes, literally it means friendly message, but in natural English it often means something like:

• a polite message
• a courteous message
• a friendly follow-up message

So the idea is not that the message is emotionally warm in a big way; it usually means the speaker wants to contact someone politely and gently, for example as a reminder or follow-up.

Because the sentence begins with a subordinate clause:

Hvis jeg ikke får svar på ansøgningen i denne uge

Then the main clause starts:

vil jeg sende en venlig besked på mandag

The comma marks the boundary between those two parts. In this sentence, that comma is standard and expected.

So the structure is:

• subordinate clause: Hvis ... uge
• main clause: vil jeg sende ...

Hvis is the normal word for if in conditional sentences like this one.

Examples:

• Hvis det regner, bliver vi hjemme. = If it rains, we stay home.
• Hvis jeg har tid, kommer jeg. = If I have time, I’ll come.

English speakers sometimes confuse hvis and om. A useful basic distinction is:

• hvis = if in conditions
• om = often whether / if in indirect questions

For example:

• Jeg ved ikke, om han kommer. = I don’t know whether he is coming.

So in your sentence, hvis is exactly the right choice.

Yes:

• Hvis = if
• jeg = I
• ikke = not
• får = get / receive
• svar = reply / answer
• på ansøgningen = to the application
• i denne uge = this week / during this week
• vil jeg sende = I will send
• en venlig besked = a polite/friendly message
• på mandag = on Monday

So the grammar is:

• condition first: Hvis jeg ikke får svar ...
• result second: vil jeg sende ...

That is a very common Danish sentence pattern.