Сестра перевязала коробку лентой и сверху прикрепила маленький бантик.

Because the subject is сестра, which is feminine singular, and both verbs are in the past tense.

In Russian past tense:

• masculine: usually ends in -л
• feminine: -ла
• neuter: -ло
• plural: -ли

So:

• сестра перевязала
• сестра прикрепила

The feminine ending shows that the sister did the actions.

Because коробку is the direct object of перевязала. It is the thing being tied/wrapped.

The noun коробка is feminine, and in the singular:

• nominative: коробка
• accusative: коробку

So:

• сестра = subject
• коробку = object

This is a very common pattern in Russian: feminine nouns ending in -а often change to -у in the accusative singular.

Because it shows the means or instrument used to do the action: the box was tied with a ribbon.

The noun лента becomes:

• nominative: лента
• instrumental: лентой (or лентою, a less common variant)

Russian often uses the instrumental case for what you use to perform an action.

Compare:

• писать ручкой — to write with a pen
• резать ножом — to cut with a knife
• перевязать лентой — to tie/wrap with a ribbon

Перевязала suggests tying something around something else, or binding/wrapping it with a ribbon or string.

In this sentence, перевязала коробку лентой means the ribbon goes around the box.

By contrast, завязать often focuses more on tying a knot or fastening something by tying it.

So:

• перевязать коробку лентой = tie/wrap the box with ribbon
• завязать бантик = tie a bow
• завязать шнурки = tie shoelaces

The prefix пере- here gives the idea of going across/around the object.

Because the subject is understood to be the same as in the first part: сестра.

Russian often omits repeated words when they are obvious from context.

So this structure is like:

• Сестра перевязала коробку лентой и (сестра) сверху прикрепила маленький бантик.

In English, we also often avoid repeating the subject:

• My sister wrapped the box with ribbon and attached a small bow on top.

Russian does this very naturally.

Сверху means on top, from above, or at the top, depending on context.

In this sentence, it means that the bow was attached on top of the box.

It is an adverb, not a noun, so it does not change form here.

Examples:

• положить сверху книгу — put a book on top
• посмотреть сверху — look from above
• сверху прикрепить бантик — attach a bow on top

Here it tells you where the bow was attached.

Because бантик is the direct object of прикрепила, and it is a masculine inanimate noun.

For masculine inanimate nouns, the accusative singular is usually the same as the nominative singular.

So:

• nominative: маленький бантик
• accusative: маленький бантик

That is why you do not see a change here, even though it is the object.

Бантик is a diminutive form of бант.

• бант = bow
• бантик = little bow / small decorative bow

The diminutive often makes the word sound:

• smaller
• cuter
• more affectionate
• more natural in everyday speech for small objects

Since the sentence already has маленький, using бантик reinforces the idea of a small decorative bow.

Because the sentence describes completed actions in the past.

• перевязала is perfective
• прикрепила is perfective

The speaker is telling us what the sister did and finished doing:

1. she tied/wrapped the box with ribbon
2. she attached a small bow on top

If the sentence used imperfective verbs, it would sound more like describing a process, repetition, or background action.

Perfective is very common when narrating a finished sequence of actions.

No, Russian word order is fairly flexible, although this version sounds natural and neutral.

Current order:

• Сестра перевязала коробку лентой и сверху прикрепила маленький бантик.

This presents the actions in a smooth, ordinary way.

You could move things around for emphasis, for example:

• Сестра лентой перевязала коробку...
• Сверху сестра прикрепила маленький бантик.
• Маленький бантик сестра прикрепила сверху.

But changing the order can shift emphasis or make the sentence sound more literary, contrastive, or marked. The original is a good standard model.

Because Russian has no articles.

English distinguishes:

• a box
• the box

Russian usually leaves that information to context.

So:

• коробку can mean a box or the box
• лентой can mean with a ribbon or with the ribbon
• маленький бантик can mean a small bow or the small bow

The listener figures it out from the situation, context, and word order if needed.

Yes, depending on the exact meaning.

Some close options are:

• наверху — at the top / up above
• сверху — on top / from above
• поверх — over, on top of

In this sentence, сверху is very natural because it describes where the bow was attached relative to the box and ribbon arrangement.

For example:

• наверху can sometimes feel more like location at the upper part
• сверху often works especially well for placement on top

So the original wording is idiomatic and clear.