Learn Swedish: Vi kastar alltid kvitton. - We always throw away receipts.

Kvitto is an ett word that ends in a vowel (ett kvitto). In Swedish, ett words that end in a vowel form their plural by just adding -n. So, ett kvitto becomes flera kvitton (several receipts).

Why does alltid come after kastar? In English we say 'always throw'.

Swedish follows the V2 (verb-second) rule, which means the main verb (kastar) must be the second piece of information in the sentence. Because vi is in the first position, the verb must come next, pushing the adverb alltid (always) after it.

The English translation says 'throw away', but is there a word for 'away' in the Swedish sentence?

No! While you can say kastar bort (throw away), it is very common in Swedish to just use the verb kastar (literally: throw) to mean throwing something in the trash.

Why use kvitton here instead of kvittona?

The sentence is talking about receipts in general, not specific ones. Kvitton means receipts (indefinite plural), while kvittona means the receipts (definite plural).