Learn Hardcore Finnish: Olen myöhässä, mutta tulen kohta.

olen = I am (1st person singular of olla, to be)
tulen = I come / I’m coming (1st person singular of tulla, to come)
You can add minä for emphasis or contrast (e.g., Minä olen myöhässä... = I (as opposed to someone else) am late...), but it’s not required.

What form is myöhässä, and why does it look like that?

myöhässä is the adjective myöhä (late) in the inessive case: myöhä + ssä.
The inessive usually means in / inside, but with time/state expressions it often means in a state of:

olen myöhässä = I am late (literally I am in lateness).
The ä in -ssä matches vowel harmony (because myöhä has front vowels y, ö, ä).

Why is it -ssä and not -ssa?

This is vowel harmony. Finnish chooses the case ending variant based on the word’s vowels:

Front vowels (y, ö, ä) → -ssä
Back vowels (a, o, u) → -ssa
Since myöhässä contains front vowels (y, ö, ä), it takes -ssä.

Does olen myöhässä mean “I’m late” or “I’m running late”? Is there a difference?

olen myöhässä covers both depending on context. It’s a general “I’m late / behind schedule.”
If you want to explicitly say you’re on your way but delayed, Finnish often uses:

Olen myöhässä, mutta olen tulossa. = I’m late, but I’m on my way.
Your original ...mutta tulen kohta already strongly suggests you’ll arrive soon.

What tense is tulen here? Is it present or future?

Formally it’s present tense (I come), but Finnish present often expresses near-future naturally:

tulen kohta = I’ll be there soon / I’m coming soon
Finnish doesn’t require a separate future tense; context words like kohta provide the future meaning.

What does kohta mean exactly? Is it like “soon,” “in a moment,” or “right away”?

kohta means soon / in a moment / shortly, and it’s fairly flexible. It usually implies not long from now, but not necessarily immediately.
Related options you might see:

pian = soon (often a bit more neutral/less “imminent”)
ihan kohta = very soon / any moment now
heti = immediately / right away

Why is the comma used: Olen myöhässä, mutta tulen kohta?

Finnish typically uses a comma before mutta (but) when it connects two full clauses that could stand as sentences:

Olen myöhässä (complete clause)
mutta tulen kohta (another clause)
So the comma is standard and expected here.

Can I change the word order, like Mutta tulen kohta, olen myöhässä?

You can, but it changes emphasis and sounds more marked. The neutral, natural order is:

Olen myöhässä, mutta tulen kohta.
If you start with mutta, you’re foregrounding the contrast (“but!”), which is possible in speech but less neutral.

Is tulen kohta the same as tulen pian?

They’re similar but not identical:

tulen kohta = I’ll come in a moment / shortly (often more immediate)
tulen pian = I’ll come soon (can feel slightly less “any second now”)
Both are correct; kohta often sounds like you’re very close to arriving.

How do you pronounce myöhässä and tulen? Anything tricky for English speakers?

Common points:

y is like the French u in lune or German ü (not like English y).
ö is like German ö (similar to the vowel in British sir for some speakers, but rounded).
h is clearly pronounced (a real h sound).
Double ss is long: myö-häs-sä (hold the s longer).
Stress is usually on the first syllable: MYÖ-häs-sä, TU-len.

Could I say Olen myöhässä, mutta tulen without kohta?

Yes, it’s grammatical, but it often sounds incomplete in meaning unless the context already implies when. kohta makes it reassuring and natural: I’m late, but I’ll be there soon.
Without it, ...mutta tulen can feel like “...but I am coming (at some point).”

What are more casual/spoken versions of this sentence?

In everyday spoken Finnish you might hear:

Oon myöhässä, mut tuun kohta.
Changes:
olen → oon (common spoken contraction)
mutta → mut
tulen → tuun
These are informal but very common in speech and texting.