Learn Hardcore Finnish: Uuni on kuuma, joten ruoka on pian valmis. - The oven is hot, so the food will be ready soon.

joten means therefore/so and introduces a result. It links two independent clauses and states a consequence.
- Example: Uuni on kuuma, joten ruoka on pian valmis.
koska means because and introduces the cause (a subordinate clause).
- Examples: Koska uuni on kuuma, ruoka on pian valmis. / Ruoka on pian valmis, koska uuni on kuuma.
siksi means for that reason; it’s an adverb starting a result clause.
- Example: Uuni on kuuma, siksi ruoka on pian valmis.

Why is there a comma before joten?

In Finnish, a comma is used before coordinating conjunctions that connect two independent clauses. Joten is one of these, so you write: …, joten …. (By contrast, you don’t normally put a comma before ja unless there’s some special reason.)

How does Finnish express “will be”? Why is it on and not a future form?

Finnish has no separate future tense. The present tense covers future meaning when the context makes it clear:

ruoka on pian valmis = the food will be ready soon. You can also use verbs of becoming for a dynamic sense:
ruoka valmistuu pian (will get ready soon)
ruoka kypsyy pian (will finish cooking soon)

Why are kuuma and valmis in that form? Do they agree with the subject?

They are predicative adjectives after olla and appear in the nominative when describing a singular count noun:

Uuni on kuuma.
Ruoka on valmis. They agree in number: plural subjects usually take a plural predicative:
Uunit ovat kuumat.

Can I say Ruoka on valmista instead of Ruoka on valmis? What’s the difference?

Yes. With mass/uncountable nouns (like ruoka, coffee, beer), Finnish often uses the partitive predicative to describe a quality or state:

Ruoka on valmista is very idiomatic, especially as an announcement that the meal is ready to be served.
Ruoka on valmis conceptualizes the meal as a single “item” that is ready. Both are correct; valmista is extremely common in this specific phrase.

Where can I place pian in the sentence?

All of these are grammatical; the difference is mostly about emphasis:

Neutral/default: … ruoka on pian valmis.
Fronted time focus: … pian ruoka on valmis.
Slightly more marked but fine: … ruoka on valmis pian.

What’s the difference between pian, kohta, and heti?

pian = soon (general, not immediate)
kohta = shortly/any moment now (often sooner than pian)
heti = immediately, right away

Could I flip the cause and effect using koska?

Absolutely:

Koska uuni on kuuma, ruoka on pian valmis. Or with the main clause first:
Ruoka on pian valmis, koska uuni on kuuma.

Does Finnish mark “the” vs “a”? How do I know if uuni means “the oven” or “an oven”?

Finnish has no articles. Uuni can mean the oven or an oven depending on context. In this kind of sentence, it usually means the specific, contextually known oven (effectively “the oven”). If you need to point to a particular one, use a demonstrative:

Tämä uuni on kuuma. (this oven)
Se uuni on kuuma. (that oven)

Why is ruoka singular when English “food” is uncountable?

Finnish ruoka can act as a mass noun (food in general) or refer to a meal. Singular ruoka is the normal way to talk about “the meal/food” in such contexts. Use plural ruoat only when you mean multiple dishes or types:

Ruoat ovat valmiita/valmiit. (the dishes are ready)

Could I use kypsä instead of valmis?

valmis = ready (to be served/eaten or finished)
kypsä = cooked/done (the cooking process has reached doneness) So you might say:
Uuni on kuuma, joten ruoka kypsyy pian. (it will finish cooking soon)
Uuni on kuuma, joten ruoka on pian valmis. (it will be ready soon)

Is there a more dynamic alternative to on pian valmis?

Yes. Use intransitive verbs of becoming:

valmistua: Ruoka valmistuu pian.
kypsyä: Ruoka kypsyy pian. With the original cause: Uuni on kuuma, joten ruoka valmistuu/kypsyy pian.

How do I negate this kind of sentence?

Use the negative verb ei + olla in the connegative form ole:

Uuni ei ole kuuma, joten ruoka ei ole pian valmis. (Meaning: the oven isn’t hot, so the food won’t be ready soon.)

Any pronunciation tips for these words?

Stress the first syllable of each word.
Long vowels matter: uu in uuni and kuuma is long; don’t shorten it. uni (short u) means sleep, while uuni (long uu) is oven.
ruoka has the diphthong uo; keep it as one smooth glide.
j in joten is like English y in yes.

Could I just use two sentences without joten?

Yes, that’s natural and common in Finnish:

Uuni on kuuma. Ruoka on pian valmis. This relies on context to imply the causal link. Using joten makes the consequence explicit.