Ні SIM-картка, ні eSIM не працюють без покриття мережі.

It means neither ... nor ....

So:

• Ні SIM-картка, ні eSIM ...
  = Neither a SIM card nor an eSIM ...

Ukrainian repeats ні before each item, just like English repeats neither / nor across two parts.

Because Ukrainian normally uses double negation.

In English, you say Neither X nor Y work.
In Ukrainian, it is natural to have:

• ні ... ні with the subjects
• не with the verb

So Ні SIM-картка, ні eSIM не працюють is the normal way to say Neither a SIM card nor an eSIM works.

Because there are two subjects: SIM-картка and eSIM.

Even though each one is singular by itself, together they make a plural idea, so Ukrainian uses the plural verb:

• SIM-картка працює = A SIM card works
• eSIM працює = An eSIM works
• Ні SIM-картка, ні eSIM не працюють = Neither a SIM card nor an eSIM works

So працюють is the expected form here.

Yes. Працювати literally means to work, to function, or to operate.

In a technical sentence like this, не працюють means:

• do not work
• do not function
• won't operate

So it is a very natural verb for devices, services, or features.

The preposition без means without, and it requires the genitive case.

So:

• без покриття = without coverage
• мережі = of the network

A very literal breakdown is:

• без = without
• покриття = coverage
• мережі = of the network

So без покриття мережі means without network coverage.

Because покриття is one of those nouns whose nominative singular and genitive singular look the same.

So even though the form does not visibly change, it is still in the genitive after без.

That is why:

• nominative: покриття
• genitive: покриття

Same spelling, different grammatical role.

Here мережа means a mobile network or cellular network.

So покриття мережі means:

• network coverage
• cellular coverage
• signal coverage

It is not talking about a literal net, and not necessarily about Wi‑Fi or the internet in general.

Yes, SIM-картка is feminine because картка is a feminine noun.

So if you described it with an adjective, that adjective would normally be feminine too.

eSIM is a borrowed technical term. In sentences like this, it is usually treated as an indeclinable noun, so its form often stays the same.

Because Ukrainian has no articles.

There is no separate word corresponding directly to English a, an, or the. So SIM-картка can mean:

• a SIM card
• the SIM card

The exact meaning depends on context.

Yes. Ukrainian word order is more flexible than English.

You can also say:

Без покриття мережі ні SIM-картка, ні eSIM не працюють.

This means the same thing, but it puts extra emphasis on the condition without network coverage.

Because Ukrainian normally uses a comma in repeated paired structures like ні ... ні.

So:

• Ні SIM-картка, ні eSIM ...

The comma separates the two coordinated parts of the pattern. This is standard punctuation here.