Коли візок повний, покупець повільно йде до каси.

In Ukrainian, the verb to be is usually omitted in the present tense.

So:

• візок повний = the cart is full
• literally: cart full

This is completely normal. Ukrainian does not usually say a present-tense є in sentences like this.

Because повний agrees with візок.

• візок is masculine singular
• so the adjective must also be masculine singular
• therefore: повний

If the noun were feminine or neuter, the form would change:

• сумка повна = the bag is full
• відро повне = the bucket is full

Here візок means a shopping cart / trolley.

In other contexts, візок can also mean things like:

• a small cart
• a stroller / pram
• a wheelchair, in some combinations

But in this sentence, because of покупець and каса, it clearly means a shopping cart.

Покупець means customer, buyer, or shopper.

Grammatically, it is a masculine noun. It can refer to:

• a specific male customer, or
• a customer in a general, generic sense

If you specifically wanted a feminine form, Ukrainian can use покупчиня, though usage varies and many speakers may prefer other wording depending on context.

Повільно is an adverb, meaning slowly.

It describes how the customer goes:

• йде повільно = goes slowly / walks slowly

It is related to the adjective повільний = slow.

A very common pattern in Ukrainian is:

• adjective in -ий
• adverb in -о

For example:

• швидкий = fast
• швидко = quickly

Both йде and іде are standard forms meaning goes / is walking.

There is usually no difference in meaning. The choice is often about euphony: Ukrainian likes to alternate sounds so the sentence flows more smoothly.

Here, after повільно, many speakers naturally prefer йде:

• повільно йде

You may also see or hear іде in other sentences.

Because йти / іти means to go on foot, to walk.

• йде = goes / walks
• їде = goes by vehicle / rides / drives

So in this sentence, the customer is walking to the checkout, not traveling in a vehicle, so йде is the correct verb.

Каси is in the genitive singular.

That is because the preposition до requires the genitive.

• каса = checkout / cash register
• до каси = to the checkout

So:

• до + genitive is a very common pattern meaning to / toward something

In a shop context, каса usually means the checkout or cash register area.

So йде до каси is naturally understood as:

• goes to the checkout
• goes to the register

In English, the best translation depends on the situation, but the Ukrainian is perfectly natural.

Коли means when, while якщо means if.

Here коли shows a time relationship or a regular sequence:

• When the cart is full, the customer goes slowly to the checkout.

It sounds like a normal, expected next step.

If you said якщо візок повний, it would sound more like a condition:

• If the cart is full...

That is possible in some contexts, but it gives a slightly different nuance.

Because Коли візок повний is a subordinate clause, and it comes before the main clause.

So Ukrainian separates them with a comma:

• Коли візок повний, покупець повільно йде до каси.

This is similar to English:

• When the cart is full, the customer walks slowly to the checkout.

Yes. Ukrainian word order is more flexible than English word order.

The given sentence is a neutral, natural version:

• Коли візок повний, покупець повільно йде до каси.

But other orders are possible if you want different emphasis, for example:

• Коли візок повний, до каси покупець йде повільно.

That said, for learners, the original version is a very good basic pattern to follow.

Most naturally, it sounds like a general situation or typical sequence:

• when the cart is full, the customer goes to the checkout

Ukrainian present tense often works this way, especially with imperfective verbs like йде.

Depending on context, it could also describe a scene, but without extra context, it is best understood as a general statement rather than a one-time event happening right now.