Broen kan bære to tonn.

Because broen is the definite singular form of bro.

• en bro = a bridge
• broen = the bridge

In Norwegian, the definite article is often attached to the end of the noun instead of being a separate word. So where English says the bridge, Norwegian says broen.

Here, kan means can in the sense of is able to or has the capacity to.

So in this sentence, it is about what the bridge is capable of supporting. It is not about permission.

Because kan is a modal verb, and after modal verbs, Norwegian normally uses the infinitive without å.

So:

• kan bære = can carry / can support

Compare:

• å bære = to carry / to bear
• Broen kan bære ... = The bridge can bear ...

This is similar to English, where we say can carry, not can to carry.

Bære literally means to carry or to bear.

In this sentence, it means to support the weight of. A bridge is not physically carrying something in its hands, of course, so bære here is best understood as bear/support.

Because tonn has the same form in the indefinite singular and plural.

• ett tonn = one ton
• to tonn = two tons

This is normal for some Norwegian nouns, especially some measurement words.

So to tonn is correct.

Because when a noun is preceded by a number, you normally do not use the indefinite article.

So:

• ett tonn = one ton
• to tonn = two tons

You would not say to et tonn.

No. Norwegian verbs do not change form for different persons the way English sometimes does.

So you get:

• jeg kan
• du kan
• han kan
• vi kan

The form kan stays the same.

The basic word order is:

subject + verb + infinitive + object/quantity

So here:

• Broen = subject
• kan = finite verb
• bære = infinitive
• to tonn = what it can bear

This matches normal main-clause word order in Norwegian.

Yes. Kan is the present-tense form.

But in Norwegian, just like in English, the present tense can also be used for a general fact. So this sentence does not have to mean only right now; it can mean that the bridge is generally rated to support that weight.

You would usually place ikke after the modal verb:

Broen kan ikke bære to tonn.

That means The bridge cannot bear two tons.

This placement is very common in Norwegian main clauses with modal verbs.

You would usually change kan to kunne:

Broen kunne bære to tonn.

That means The bridge could bear two tons or was able to bear two tons, depending on context.