Vid kassan frågar hon om vi behöver en påse.

Vid kassan means at the checkout, at the register, or at the till.

• vid = at, by, next to
• kassan = the checkout / the cash register

So this phrase places the action in the context of paying in a shop.

This is because Swedish follows the V2 rule in main clauses: the finite verb usually comes in the second position.

Here, the sentence starts with Vid kassan, so that takes the first position. The verb frågar must then come second:

• Vid kassan frågar hon ...

If you started with the subject instead, you would say:

• Hon frågar om vi behöver en påse.

Both are correct, but the first one emphasizes the setting: at the checkout.

Here, om means if or whether.

So:

• frågar hon om vi behöver en påse = she asks if we need a bag

This is a very common use of om after verbs like fråga when introducing an indirect yes/no question.

Be careful: om can also mean about, but not in this sentence.

Behöver is the present tense form of the verb behöva (to need).

• infinitive: behöva
• present: behöver

Since the sentence says we need, Swedish uses the present tense form:

• vi behöver = we need

Swedish verbs do not change according to the subject, so:

• jag behöver
• du behöver
• vi behöver
• hon behöver

all use behöver in the present tense.

Swedish does not use a dummy auxiliary like English do in questions.

English needs:

• Do we need a bag?

Swedish simply uses the verb itself:

• Behöver vi en påse?

And in an indirect question, as in your sentence:

• ... om vi behöver en påse

So there is no separate word corresponding to English do here.

Because påse is a common gender noun in Swedish, and common gender nouns take en.

• en påse = a bag

In Swedish, nouns are usually either:

• en-words
• ett-words

Påse is an en-word, so:

• en påse
• påsen = the bag

Because the sentence means a bag, not the bag.

• en påse = a bag / any bag
• påsen = the bag

At a checkout, the cashier is usually asking whether you need a bag, not referring to one specific already-known bag.

It comes from the noun kassa plus the definite ending.

• kassa = checkout / cash register
• kassan = the checkout / the register

For many en-words, Swedish adds -n to make them definite:

• en påse → påsen
• en kassa → kassan

So instead of using a separate word for the, Swedish often adds the definite ending directly to the noun.

Not necessarily. Påse is a general word for a bag, especially the kind of bag you get in a shop.

Depending on context, it could mean:

• a plastic bag
• a paper bag
• a carrier bag

At a supermarket or store checkout, en påse usually means the shopping bag offered to customers.

Yes, but that would be a direct question:

• Behöver vi en påse? = Do we need a bag?

Your original sentence contains an indirect question after frågar:

• Vid kassan frågar hon om vi behöver en påse.
• At the checkout, she asks if we need a bag.

So both are correct, but they have different structures.

It usually means at the checkout / at the register, meaning the place where you pay.

It does not specifically mean with the cashier as a person. If you wanted to emphasize the person, Swedish would use something else, such as a phrase involving kassör or kassörska in the right context.

So vid kassan is mainly about the location or situation in the store.