Продавец обернул коробку лентой.

• Продавец = the seller / shop assistant. It is the subject of the sentence, in the nominative case.
• обернул = wrapped. This is a past tense, masculine singular, perfective verb form.
• коробку = the box. It is the direct object, so it appears in the accusative case.
• лентой = with ribbon / using ribbon. It is in the instrumental case, showing the material or means used.

So the structure is basically:

[subject] + [verb] + [object] + [instrument/material]

Because коробка is the thing being acted on: the seller wrapped the box.

The verb обернуть takes a direct object, and direct objects are usually in the accusative.

• Nominative: коробка
• Accusative: коробку

Since коробка is an inanimate feminine noun, the accusative singular ends in -у here.

Because it tells you what was used to wrap the box or what the box was wrapped with.

In Russian, the instrumental case often expresses:

• the tool used to do something
• the material used
• the means by which something happens

So:

• лента = ribbon
• лентой = with ribbon / using ribbon

This is very natural after verbs like обернуть when you say what something was wrapped in or with.

Russian often expresses meanings like with, by, or using just through the instrumental case, without needing a preposition.

So English says:

• wrapped the box with ribbon

Russian can simply say:

• обернул коробку лентой

The case ending -ой already signals that idea.

обернул is the past tense masculine singular form of the verb обернуть.

Here is what that tells you:

• past tense: the action happened in the past
• masculine singular: the subject is grammatically masculine singular
• perfective: the action is seen as completed

So обернул means something like:

• wrapped
• finished wrapping

If the subject were feminine, you would get:

• Продавщица обернула коробку лентой.

If plural:

• Продавцы обернули коробку лентой.

Russian uses perfective aspect when the speaker views the action as a completed whole.

обернул suggests:

• the seller completed the wrapping
• the result matters: the box ended up wrapped

The imperfective partner is usually оборачивать:

• Продавец оборачивал коробку лентой.
  = The seller was wrapping the box / used to wrap the box with ribbon.

So the difference is roughly:

• обернул = wrapped it, finished it
• оборачивал = was wrapping, used to wrap, or describes the process

Not always. Лента can mean several related things, such as:

• ribbon
• band
• strip
• tape, in some contexts

In this sentence, ribbon is a very natural translation, especially if we imagine gift wrapping. But Russian itself is a little broader: it focuses on the strip-like material used.

So depending on context, it could be:

• wrapped the box with ribbon
• wrapped the box with tape/band

If the meaning shown to the learner is ribbon, that is a good, natural interpretation.

Russian has no articles like a, an, or the.

So:

• Продавец can mean a seller or the seller
• коробку can mean a box or the box

Which one sounds best depends on context.

English must choose, but Russian usually leaves that unstated unless something else makes it clear.

Yes. Russian word order is fairly flexible because the case endings show each word’s role.

The neutral order here is:

• Продавец обернул коробку лентой.

But you could also see things like:

• Коробку продавец обернул лентой.
• Лентой продавец обернул коробку.

These versions are still grammatical, but they shift focus or emphasis.

Very roughly:

• sentence-initial коробку emphasizes the box
• sentence-initial лентой emphasizes the ribbon/material

So word order in Russian often affects information structure, not basic grammatical relations.

Two things point to that:

1. Продавец is grammatically a masculine noun
2. The verb form обернул is masculine singular past tense

In past tense, Russian verbs agree with the subject in gender and number:

• masculine: обернул
• feminine: обернула
• neuter: обернуло
• plural: обернули

So this sentence presents the seller as grammatically masculine.

They are close, but not always identical.

• обернуть often emphasizes wrapping around something
• завернуть often means to wrap up something, especially as a package

In many real situations, both can be possible:

• Продавец обернул коробку лентой.
• Продавец завернул коробку лентой.

But the exact nuance can depend on context. For learners, it is useful to think of обернуть as strongly connected with the idea of wrapping something around/on all sides.

A helpful stress pattern is:

• продавЕц
• обернУл
• корОбку
• лентОй

So you can say it roughly like:

прадавЕц абернУл карОбку лентОй

That rough English-style spelling is only approximate, but the stress placement is important.

Yes, the Russian phrasing can suggest that the ribbon was the material used to wrap or cover the box, not just something attached to it.

With обернуть + object + instrumental, the instrumental often gives the material wrapped around the object.

So the sentence most naturally means something like:

• the seller wrapped the box with ribbon
• the seller wound ribbon around the box

If you wanted to express only that a ribbon was added or tied on, Russian might use a different verb depending on the exact situation.