Замість того щоб відкрити упаковку, я зберіг її.

Замість того щоб means instead of followed by an action.

It introduces a contrast between:

• the action that could have happened, and
• the action that actually happened.

In this sentence:

• замість того щоб відкрити упаковку = instead of opening the package

A very useful pattern is:

замість того щоб + infinitive

For example:

• Замість того щоб працювати, він спить. = Instead of working, he is sleeping.
• Замість того щоб подзвонити, вона написала. = Instead of calling, she wrote.

So here, the speaker is saying that opening the package did not happen; something else happened instead.

Because after замість того щоб, Ukrainian commonly uses the infinitive to name the action.

So:

• відкрити = to open

This is similar to English instead of opening or instead of to open, though English uses the -ing form, while Ukrainian uses the infinitive.

Structure:

• замість того щоб відкрити упаковку
• literally: instead of that to open the package

In natural English, we translate it more smoothly as instead of opening the package.

This is about aspect.

• відкрити = perfective → to open, as a completed action
• відкривати = imperfective → to be opening / to open repeatedly / to open in a general process sense

Here, the speaker means a single completed action that could have happened: to open the package. That is why відкрити sounds natural.

So the sentence presents a contrast like:

• possible completed action: відкрити упаковку
• actual completed action: зберіг її

If you used відкривати, it would sound more like talking about the process or repeated action, which is less natural here.

Because упаковку is in the accusative case.

The base form is:

• упаковка = package / packaging / wrapper

Since it is the direct object of відкрити (to open), it goes into the accusative:

• відкрити що? → упаковку

For many feminine nouns ending in -а, the accusative singular changes to -у:

• книга → книгу
• машина → машину
• упаковка → упаковку

So упаковку simply means the package as the thing being opened.

Зберіг is the past tense of зберегти, a perfective verb.

It can mean:

• kept
• saved
• preserved

In this sentence, the most natural English translation is usually kept it.

Grammar details:

• зберіг = masculine singular past
• used with я because the speaker is male, or the sentence is written from a masculine perspective

If the speaker were female, it would be:

• я зберегла її

So:

• я зберіг її = I kept/saved it (male speaker)
• я зберегла її = I kept/saved it (female speaker)

Її means her or it, depending on context.

Here it means it, because it refers back to упаковку:

• упаковка is a feminine noun
• so the pronoun referring to it is її

In this sentence:

• я зберіг її = I kept it

Grammatically, її is the direct object, so it is in the accusative.

This is very common in Ukrainian: once the noun has already been mentioned, you can replace it with a pronoun.

Because the sentence begins with a subordinate phrase/clause:

• Замість того щоб відкрити упаковку,
• я зберіг її.

The comma separates the introductory instead-of clause from the main clause.

So the structure is:

• subordinate idea: instead of opening the package
• main statement: I kept it

This is similar to English punctuation in a sentence like:

• Instead of opening the package, I kept it.

Yes. Ukrainian word order is flexible.

This sentence:

• Замість того щоб відкрити упаковку, я зберіг її.

could also be rearranged, for example:

• Я зберіг її замість того щоб відкрити упаковку.

Both are grammatical. The difference is mainly emphasis:

• starting with Замість того щоб... highlights the contrast first
• starting with Я зберіг її... highlights the speaker’s action first

Ukrainian often moves parts of the sentence around for focus, style, or rhythm.

Упаковка can mean several related things, depending on context:

• package
• packaging
• wrapper
• container/packing

So in different sentences it might refer to:

• the outer wrapping
• the retail package
• the packaging material

In this sentence, it most likely means the package / packaging of something that could have been opened.

Yes, you may sometimes see замість того, щоб in other sentence structures. But in your sentence, замість того щоб is functioning as a single unit at the start, and the important comma is the one after the whole phrase:

• Замість того щоб відкрити упаковку, я зберіг її.

For a learner, the safest thing is to recognize the expression as a fixed pattern:

замість того щоб + infinitive

and then remember that when this whole phrase comes before the main clause, it is followed by a comma.