Kom jij straks naar boven?

Because this is a yes/no question. In Dutch, yes/no questions usually put the finite verb first and the subject after it.

• Statement: Jij komt straks naar boven. = You are coming upstairs later.
• Question: Kom jij straks naar boven? = Are you coming upstairs later?

This is a very common Dutch word order pattern.

Jij is the stressed form of je.

In many everyday questions, a Dutch speaker would more neutrally say:

• Kom je straks naar boven?

Using jij often adds a little emphasis, as in:

• Are you coming upstairs later?

So Kom jij straks naar boven? can sound slightly more pointed, contrastive, or attentive than Kom je straks naar boven?, though both are correct.

Straks usually means something like later, in a bit, or soon/later on, depending on context.

It often refers to a time that is:

• not right now
• but usually not very far in the future

So in this sentence, straks suggests:

• later today
• in a little while
• shortly, but not immediately

It is a very common Dutch word, and its exact timing depends on the situation.

Because naar boven expresses movement in the direction of upstairs/upward.

• boven = upstairs / up / above (location)
• naar boven = upward / upstairs (direction toward that place)

Compare:

• Ik ben boven. = I’m upstairs.
  (location)
• Ik kom naar boven. = I’m coming upstairs.
  (movement)

So in Kom jij straks naar boven?, the speaker is asking about going/moving upstairs, not just being there.

Not always. Literally, it means up/upward. But in many everyday situations, especially inside a house or building, it naturally means upstairs.

For example:

• in a house: naar boven = upstairs
• on a ladder or hill: it could mean simply up

So the exact English translation depends on the setting.

Dutch often uses komen when the movement is toward the speaker or toward a place that is relevant from the speaker’s point of view.

• Kom jij straks naar boven? = Are you coming upstairs later?
• Ga jij straks naar boven? = Are you going upstairs later?

Both can be possible, but the choice depends on perspective.

If the speaker is upstairs, or thinks of the upstairs area as the destination relative to them, komen is very natural.
If the speaker is thinking more generally about the other person’s movement, gaan may also work.

So komen here is about the speaker’s viewpoint.

No, not in the same way as a true separable verb like opstaan or meekomen.

Here you have:

• the verb komen
• plus the prepositional phrase naar boven

So naar boven is not a prefix attached to the verb. It is just a phrase telling you the direction.

That is why the sentence works like this:

• Kom jij straks naar boven?
• Jij komt straks naar boven.

The verb is simply komen.

Yes, Dutch adverbs like straks can often move around, but some positions sound more natural than others.

Very natural:

• Kom jij straks naar boven?

Also possible:

• Kom jij naar boven straks?

But that second version often sounds a bit less neutral or more marked.
The original sentence is the most natural everyday order.

The neutral statement would be:

• Jij komt straks naar boven.

Or, more commonly in everyday speech:

• Je komt straks naar boven.

That follows normal Dutch main-clause word order:

• subject
• finite verb
• time expression
• direction/place

A rough guide:

• jij sounds somewhat like yay or yeye, but with the Dutch ij sound, which is not exactly the same as English.
• boven sounds roughly like BOH-vuhn

A few details:

• Dutch j sounds like English y
• ij is a diphthong; English speakers often approximate it imperfectly at first, and that is normal
• the o in boven is a long o
• the final -en is usually a weak syllable, like uh(n)

You do not need perfect pronunciation right away to be understood.