Learn Hardcore Norwegian: Jeg kjøper grønnsaker slik at vi kan lage suppe i kveld. - I buy vegetables so that we can make soup tonight.

slik at is a subordinating conjunction that introduces a purpose clause, equivalent to so that in English. In Jeg kjøper grønnsaker slik at vi kan lage suppe, it shows why the action is done (to make soup).
for at also introduces purpose clauses and often pairs with modal verbs like skal (e.g. Jeg trener for at jeg skal bli sterk).
The conjunction så can appear in casual speech to link to a purpose or result (e.g. Jeg trener mye så jeg kan bli sterk), but in writing slik at or for at provides clearer purpose meaning.

Why is the word order vi kan instead of kan vi?

Because slik at introduces a subordinate clause, and subordinate clauses in Norwegian use Subject–Verb (S–V) order. Main clauses follow the V2 rule (verb-second), but after subordinating conjunctions like slik at, the finite verb comes right after the subject. Hence vi kan, not kan vi.

Why is there no å before lage after kan?

Modal verbs in Norwegian—kan, må, skal, vil—are directly followed by the bare infinitive, without å. So you say kan lage, not kan å lage.

Why is kjøper in the present tense instead of an English-like continuous form?

Norwegian does not have a separate progressive aspect. The simple present tense covers both general actions and ongoing or near-future events. Thus Jeg kjøper grønnsaker can mean “I buy vegetables,” “I am buying vegetables,” or “I will buy vegetables soon.” To emphasize an ongoing action you can use holder på å: Jeg holder på å kjøpe grønnsaker.

Why is there no article before grønnsaker? Can I say noen grønnsaker instead?

Indefinite plural nouns in Norwegian can appear without an article to express a non-specific category: grønnsaker = vegetables in general. You may add noen to indicate some: noen grønnsaker. If you refer to particular vegetables known in context, you use the definite plural de grønnsakene.

What does i kveld modify, and how could you express that you are buying vegetables tonight instead?

Here i kveld is part of the subordinate clause slik at vi kan lage suppe i kveld, so it tells when we will make the soup. To make i kveld refer to the buying action, move it to the main clause. For example:
• I kveld kjøper jeg grønnsaker slik at vi kan lage suppe.
• Jeg kjøper grønnsaker i kveld slik at vi kan lage suppe.

How do you pronounce the kj sound in kjøper and the vowel ø in grønnsaker?

The kj digraph is pronounced as a voiceless palatal fricative [ç], similar to the German ich-sound—place your tongue close to the hard palate and exhale softly.
The vowel ø is a mid-front rounded vowel [ø], akin to the French peu. To approximate it, round your lips as if pronouncing bed while keeping your tongue position closer to that of eat.