Vi måste tömma papperskorgen innan gästerna kommer.

Because måste is a modal verb. After modal verbs in Swedish, the next verb normally stays in the infinitive without att.

Common pattern:

• Jag måste gå = I must leave
• Vi kan simma = We can swim
• Hon vill äta = She wants to eat

So Vi måste tömma papperskorgen is the normal structure.

Måste expresses necessity or obligation. Depending on context, it can match either must or have to in English.

In everyday English, must can sound stronger or more formal, while Swedish måste is very common and often feels closer to have to:

• Vi måste gå nu = We have to leave now

A useful thing to remember:

• jag måste
• du måste
• vi måste

It does not change for person the way English sometimes does.

Tömma means to empty.

It is usually used with a direct object — you empty something:

• tömma papperskorgen = empty the wastebasket
• tömma flaskan = empty the bottle

It is related to the adjective tom, which means empty:

• Papperskorgen är tom = The wastebasket is empty

So:

• tom = empty
• tömma = to empty

Because Swedish forms compound nouns very freely, and they are usually written as one word.

Here:

• papper = paper
• korg = basket

Together:

• papperskorg = paper basket / wastebasket

The -s- in the middle is a common linking sound in compounds. It does not have a separate meaning by itself.

So papperskorg is literally something like paper-basket, but in natural English it usually means wastebasket, trash can, or bin, depending on context.

The -en is the Swedish definite ending, meaning the.

So:

• en papperskorg = a wastebasket
• papperskorgen = the wastebasket

In Swedish, the definite article is usually attached to the end of the noun instead of being a separate word.

Also notice that in a compound noun, the definite ending goes on the whole compound, not on the first part:

• papperskorg → papperskorgen

For the same reason: Swedish usually puts the at the end of the noun.

Here is the full pattern:

• en gäst = a guest
• gästen = the guest
• gäster = guests
• gästerna = the guests

So gästerna already includes the. You do not need a separate word before it.

A useful extra note: if there is an adjective, Swedish often uses double definiteness:

• de trevliga gästerna = the nice guests

But with just the noun by itself, gästerna is enough.

Innan means before.

In this sentence, it introduces a clause:

• innan gästerna kommer = before the guests come / before the guests arrive

So here innan is acting as a subordinating conjunction.

It can also be used in other kinds of expressions:

• innan middagen = before dinner
• innan vi går = before we leave

Because Swedish often uses the present tense for future events when the time is already clear from the context.

Here, innan already shows that the guests’ arrival is something that will happen later. So Swedish does not need a separate future form.

That is why:

• innan gästerna kommer

can mean:

• before the guests come
• before the guests are coming
• more naturally in English: before the guests arrive

This is very normal in Swedish.

Literally, kommer is from komma, which means to come. But in sentences like this, English often translates it more naturally as arrive.

So:

• gästerna kommer literally = the guests come
• natural English here = the guests arrive

Both ideas are built into the Swedish sentence, but arrive is often the best English choice in this context.

Then Swedish uses its normal verb-second pattern in the main clause.

So you can say:

• Vi måste tömma papperskorgen innan gästerna kommer.

Or:

• Innan gästerna kommer måste vi tömma papperskorgen.

Notice that after the fronted innan clause, Swedish says:

• måste vi not
• vi måste

That inversion is very common in Swedish main clauses after something has been placed first.