Kova dolu olunca onu merdivenden taşımak zor oluyor.

Olunca comes from the verb olmak (to be / to become / to happen) plus the suffix -ınca / -ince.

So:

• olmak = to become, to be
• olunca = when it becomes / when it is / once it is

In this sentence, Kova dolu olunca means something like:

• when the bucket is full
• once the bucket is full

This structure is very common in Turkish for giving a condition in a natural, everyday way.

Because dolu is an adjective meaning full.

• dolu = full
• olmak = to be / become

So dolu olunca literally means when it is/becomes full.

By contrast, dolmak is a different verb meaning to fill up / become full.

So both can work in many contexts, but they are built differently:

• Kova dolunca = when the bucket fills up / becomes full
• Kova dolu olunca = when the bucket is full

The sentence you were given uses the adjective + olmak structure.

It often means when, but depending on context it can feel a bit like if/when.

Here, Kova dolu olunca suggests:

• when the bucket is full
• once the bucket gets full

It refers to a situation that leads to the next result: carrying it on the stairs becomes difficult.

So in English, the most natural translation is usually when or once, not a strong hypothetical if.

Because onu is the accusative form of o.

• o = he / she / it / that
• onu = him / her / it / that (as a direct object)

In this sentence, the thing being carried is the bucket, so it is the direct object of taşımak (to carry).

• onu taşımak = to carry it

Turkish often uses the accusative when the object is specific and definite. Here the bucket is a specific thing already mentioned, so onu is correct.

It refers back to kova (bucket).

So:

• Kova dolu olunca = when the bucket is full
• onu ... taşımak = to carry it

Even though kova is not repeated, Turkish commonly uses a pronoun like onu to refer back to something already mentioned.

Yes, -den / -dan often means from, but it can also mark the route or passage used for movement.

So merdivenden taşımak can mean something like:

• to carry it via the stairs
• to carry it on the stairs
• to carry it up/down the stairs depending on context

This is similar to other Turkish expressions where -den shows the path:

• kapıdan girmek = to enter through the door
• pencereden bakmak = to look through the window

So here merdivenden does not have to mean literally from the stairs. It can mean movement involving the stairs as the route.

Not by itself.

Merdivenden only tells you that the stairs are involved as the route. The exact direction is not explicitly stated.

Depending on context, it could mean:

• up the stairs
• down the stairs
• more generally on/along the stairs

If Turkish wants to be clearer, it can add words like:

• merdivenden yukarı = up the stairs
• merdivenden aşağı = down the stairs

So in your sentence, the idea is simply that carrying the full bucket on the stairs is difficult.

Because the sentence is talking about the action itself as a general activity: carrying it.

• taşımak = to carry / carrying

Turkish often uses the infinitive in -mak / -mek when an action is treated like a noun or concept.

So:

• onu merdivenden taşımak = carrying it on the stairs

This whole infinitive phrase acts like the subject of zor oluyor:

• Carrying it on the stairs becomes difficult.

Both are possible, but they feel slightly different.

• ... taşımak zor. = ... carrying it is difficult.
• ... taşımak zor oluyor. = ... carrying it becomes difficult / tends to be difficult / is difficult in practice.

Oluyor adds a more dynamic, real-life sense. It can suggest:

• the situation results in difficulty
• it turns out to be difficult
• it becomes difficult under those conditions

So zor oluyor sounds very natural in spoken Turkish when describing what happens in a certain situation.

Oluyor is the present continuous / general present-use form of olmak.

Here it does not literally mean only is becoming every single time in a dramatic sense. In everyday Turkish, oluyor is often used to express:

• it becomes
• it is
• it turns out to be
• it ends up being

So zor oluyor is a very natural way to say:

• it gets difficult
• it’s difficult
• it becomes hard

depending on context.

Turkish word order is flexible, but this order is natural.

The core part is:

• onu = it
• merdivenden = on/via the stairs
• taşımak = to carry

Turkish often places the object and other details before the infinitive or the main verb. So this phrase is structured in a typical Turkish way:

• onu merdivenden taşımak = to carry it on the stairs

Other orders may be possible for emphasis, but this version is straightforward and normal.

Yes. A common alternative is:

• Kova doluyken onu merdivenden taşımak zor oluyor.

Doluyken means when it is full / while it is full.

The difference is small:

• dolu olunca = when it becomes/is full; once it is full
• doluyken = while it is full / when it is in a full state

Both are natural. The version with olunca emphasizes the condition leading to the difficulty.

Turkish does not have articles like English a and the.

So kova can mean:

• a bucket
• the bucket

The exact meaning depends on context.

In this sentence, because the next part uses onu (it), the bucket is understood as a specific bucket in context.

Yes.

• Kova dolu. = The bucket is full.

This is a normal Turkish sentence with an adjective predicate. Turkish often does not need a separate word for is in the present tense.

So:

• Kova dolu = The bucket is full
• Kova dolu olunca = When the bucket is full

The olunca part is what turns it into a when/once clause.

A very literal breakdown would be:

• Kova = bucket
• dolu = full
• olunca = when it is/becomes
• onu = it
• merdivenden = via/on/from the stairs
• taşımak = to carry
• zor = difficult
• oluyor = becomes / is

So, very literally:

When the bucket is full, carrying it on the stairs becomes difficult.

A more natural English version might be:

• When the bucket is full, it’s hard to carry it on the stairs.
• When the bucket is full, carrying it up/down the stairs is difficult.

The exact English wording depends on context.