Wir müssen jetzt handeln.

This is because müssen is a modal verb.

In a normal main clause in German, the conjugated verb goes in second position. Here, müssen is the conjugated verb:

• Wir = subject
• müssen = conjugated modal verb
• jetzt handeln = the rest of the predicate

When a modal verb is used, the main action verb usually stays in the infinitive and goes to the end of the clause.

So:

• Wir müssen jetzt handeln.
• literally: We must now act.

This pattern is very common in German:

• Ich kann Deutsch sprechen.
• Sie will morgen kommen.

Müssen is the infinitive, and müssen here is also the 1st person plural / 3rd person plural present-tense form.

With wir, the verb form is:

• wir müssen = we must / we have to

A quick present-tense chart:

• ich muss
• du musst
• er/sie/es muss
• wir müssen
• ihr müsst
• sie/Sie müssen

So in this sentence, wir müssen simply means we must or we have to.

Because after a modal verb, German normally uses the bare infinitive — that is, the infinitive without zu.

So you say:

• Wir müssen handeln.
• Ich kann kommen.
• Sie will gehen.

Not:

• Wir müssen zu handeln. ❌

This is similar to English, where we say:

• We must act
• not We must to act

Here, handeln means to act or to take action.

That is the most natural meaning in this sentence:

• Wir müssen jetzt handeln. = We have to act now.

But handeln can have other meanings in different contexts, for example:

• von etwas handeln = to be about something
• mit etwas handeln = to trade in something

So context matters. In this sentence, it clearly means to take action.

Yes, jetzt can move, but its position affects emphasis and style.

In Wir müssen jetzt handeln, jetzt sits in the middle field of the sentence, which is very natural and neutral.

Other possible versions include:

• Jetzt müssen wir handeln. = Now we must act.
  This gives jetzt stronger emphasis because it comes first.

• Wir müssen handeln, jetzt.
  This is possible in speech, but less neutral and more dramatic.

The standard, everyday version is:

• Wir müssen jetzt handeln.

Often yes, but not always exactly.

Müssen usually means:

• must
• have to

So this sentence could be translated as either:

• We must act now.
• We have to act now.

In many situations, German müssen covers both ideas, while English sometimes distinguishes between stronger must and more everyday have to.

So the German sentence is perfectly natural, and the exact English wording depends on tone and context.

A rough English-friendly guide:

• Wir ≈ veer
• müssen ≈ something like MUH-sen, but with the ü sound, which does not exist exactly in English
• jetzt ≈ yetst
• handeln ≈ HAHN-deln

A few pronunciation notes:

• w in German sounds like English v
• ü is a front rounded vowel; if you know French u, it is similar
• z in German sounds like ts
• d in handeln may sound softer because of the surrounding sounds

A rough full approximation: Veer MUH-sen yetst HAHN-deln

Yes, handeln is basically a regular weak verb.

Its infinitive is handeln, and some present-tense forms are:

• ich handle
• du handelst
• er/sie/es handelt
• wir handeln
• ihr handelt
• sie/Sie handeln

One small thing learners notice is the extra e in some forms like ich handle. That happens because the verb stem ends in -dl, which is awkward to pronounce without an extra vowel.

Its past participle is:

• gehandelt

So yes, it behaves regularly.

In a yes/no question, the conjugated verb comes first:

• Müssen wir jetzt handeln? = Must we act now? / Do we have to act now?

This is a standard German word-order change:

• statement: Wir müssen jetzt handeln.
• question: Müssen wir jetzt handeln?

If you want a question with a question word, you could say:

• Warum müssen wir jetzt handeln? = Why do we have to act now?

The most natural negation is usually with nicht:

• Wir müssen jetzt nicht handeln.

This usually means:

• We do not have to act now.
• We don’t need to act now.

Important: this does not usually mean We must not act now.

If you want must not, German often uses:

• Wir dürfen jetzt nicht handeln. = We must not act now.

So:

• nicht müssen = do not have to
• nicht dürfen (or dürfen nicht) = must not / are not allowed to

That is a very important distinction.

A common past form is with mussten:

• Wir mussten jetzt handeln. = We had to act now.

In spoken German, people also often use the perfect tense, though modal verbs are very commonly used in the simple past too.

Simple past:

• Wir mussten jetzt handeln.

Perfect:

• Wir haben jetzt handeln müssen.

For learners, the simple past version is often easier and very common with modal verbs.