De skal giftes til sommer.

It can be either.

• de usually means they
• De can be the formal/polite you

Because this word is at the start of the sentence, it is capitalized anyway, so you cannot tell from capitalization alone. You need context.

So this sentence can mean either:

• They are getting married this summer
• You are getting married this summer (formal)

In modern everyday Danish, the formal you is much less common than it used to be, so learners will often see de as they.

Formally, skal is present tense, but the sentence refers to the future.

Danish often talks about the future without a special future ending. It uses:

• the present tense
• modal verbs like skal or vil
• a time expression such as til sommer

So De skal giftes til sommer is present in form, but future in meaning.

Not necessarily. Skal can mean must / have to, but in this sentence it usually means something more like:

• are going to
• are set to
• are getting married

It often gives a sense that the event is planned or decided.

So here skal is not mainly about obligation. It is more about an arranged future event.

Giftes is an -s form of the verb, and with marriage it is a very common way to say get married.

Danish -s forms can have passive or middle-like meanings. In this sentence, giftes does not feel like a literal English passive. It is just the normal Danish way to talk about the event of getting married.

After skal, Danish uses the infinitive, and here that infinitive is giftes:

• at giftes = to get married

So skal giftes is completely normal.

Yes, often you can.

If the meaning is they, then de skal gifte sig til sommer is also possible. It is very close in meaning to de skal giftes til sommer.

A rough difference is:

• giftes = a very common fixed way to say get married
• gifte sig = the reflexive version, also common

In practice, both are used. Learners should recognize both.

This is an important distinction:

• giftes = get married → the event
• være gift = be married → the state

So:

• De skal giftes til sommer = the wedding will happen in summer
• De er gift = they are married

English often uses are getting married for the first idea.

Til sommer means this coming summer or next summer, depending on when you are speaking.

It does not mean a literal to summer in English. It is a time expression.

So if someone says this in winter or spring, til sommer normally means the upcoming summer.

Danish often uses fixed time expressions without an article. Til sommer is one of those expressions.

Compare:

• til sommer = this coming summer / next summer
• i sommer = this summer, often the current or just-finished summer
• om sommeren = in summer in general, every summer, as a habit

So:

• De skal giftes til sommer = one specific upcoming summer
• De rejser om sommeren = they travel in summer generally

Yes. This is normal Danish main-clause word order.

• De = subject
• skal = finite verb
• giftes = infinitive
• til sommer = time expression

Danish main clauses usually place the finite verb in the second position. That is exactly what happens here.

If you move the time phrase to the front, the verb still stays second:

• Til sommer skal de giftes.

That is also completely natural.