Learn Hardcore Finnish: Laitan kuvan kansioon myöhemmin. - I will put the picture in the folder later.

Finnish often uses the present tense to talk about future actions when the time is clear from context (here: myöhemmin = later).
So laitan literally means I put / I place, but in this sentence it naturally works as I’ll put.

What verb is laitan, and what does it mean compared with other “put” verbs?

Laitan is the 1st person singular present form of laittaa (to put / place / set / add / fix, depending on context).
It’s one of the most common everyday “put” verbs in Finnish. Another option is panna, but laittaa is usually the safer, more neutral choice.

Why is it kuvan and not kuva?

kuvan is kuva + -n, showing the object as a total/complete object (often called the accusative in Finnish grammar; it looks like the genitive -n).
Here the idea is: you will put the whole picture into the folder (a completed action), so kuvan fits.

When would it be Laitan kuvaa… instead of Laitan kuvan…?

You’d use the partitive (kuvaa) when the object is partial, ongoing, indefinite, or not completed. For example:

Laitan kuvaa kansioon could suggest you’re in the process of adding/uploading (less common phrasing), or not focusing on completion. In most practical “I’ll put/upload the picture into the folder” contexts, kuvan is the natural choice.

What case is kansioon, and why does it end in -oon?

kansioon is the illative case, meaning into something.
The base word is kansio (folder), and the illative singular is formed as kansio + on → kansioon.
So:

kansio = a folder
kansiossa = in the folder
kansioon = into the folder

Is kansioon always “into a folder,” or can it mean “into the folder”?

Finnish doesn’t have articles (a/the), so kansioon can mean into a folder or into the folder. The intended meaning comes from context (e.g., which folder you’ve already been talking about).

Why is the word order Laitan kuvan kansioon myöhemmin? Could I move words around?

This is a very neutral, common order: verb + object + destination + time.
You can move parts for emphasis:

Myöhemmin laitan kuvan kansioon. (emphasizes later)
Kansioon laitan kuvan myöhemmin. (emphasizes into the folder)
The basic meaning stays the same, but the focus changes.

What part of speech is myöhemmin, and how is it formed?

myöhemmin is an adverb meaning later.
It comes from the comparative form myöhempi (later / more late) and the adverbial ending -n used in some time adverbs. You mostly just learn myöhemmin as a fixed, common word.

How do you pronounce kansioon and myöhemmin?

Key points:

kansioon: the oo is a long vowel; the final -n is clearly pronounced. Roughly kan-sio-on (with the o lengthened).
myöhemmin: y and ö are front vowels; keep them distinct. Stress is on the first syllable: MYÖ-hem-min.

Could I say Lisään kuvan kansioon myöhemmin instead of Laitan…?

Yes, but it changes the nuance:

laitan = put/place (very general)
lisään = add/insert (sounds a bit more like adding something to a collection or a document)
If you’re talking about adding a file to a folder (especially digitally), both can work, but laitan is the most neutral everyday choice.