Коли відправник надсилає файл через мережу, одержувач одразу бачить його на екрані.

Here коли means when.

In this sentence, коли introduces a time clause: When the sender sends a file through the network, the recipient immediately sees it on the screen.

In sentences like this, коли often has a general meaning close to whenever or when(ever) in English:

• Коли відправник надсилає файл... = When / Whenever a sender sends a file...

So it is not talking about one specific moment only; it can describe a regular process or general rule.

Because Ukrainian puts a comma between a subordinate clause and the main clause.

The first part is the subordinate clause:

• Коли відправник надсилає файл через мережу

The second part is the main clause:

• одержувач одразу бачить його на екрані

So the comma is required, just like in English:

• When the sender sends a file through the network, the recipient immediately sees it on the screen.

Both are in the nominative singular, because both are subjects of their own clauses.

• відправник = sender
• одержувач = recipient

In the first clause, відправник is the one doing the action надсилає. In the second clause, одержувач is the one doing the action бачить.

These are also common Ukrainian noun patterns for people who perform a role:

• відправник = sender
• одержувач = receiver / recipient
• compare similar formations like учасник = participant

надсилає is the imperfective present form of надсилати.

That is used because the sentence describes a process or general repeated action:

• Коли відправник надсилає файл...
  = When/whenever the sender sends a file...

The imperfective is natural for habitual, repeated, or ongoing actions.

A related perfective verb is:

• надіслати = to send (as a completed action)

So:

• надсилати / надсилає = sending, sends, is sending
• надіслати / надішле = send, will send, send off completely

In a general technical statement like this, the imperfective is the normal choice.

It is accusative, but for an inanimate masculine singular noun, the accusative often looks exactly like the nominative.

So:

• nominative: файл
• accusative: файл

That is why nothing changes in form.

This is very common in Ukrainian:

• читати текст = to read a text
• відкрити файл = to open a file
• надсилати лист = to send a letter

But with animate masculine nouns, accusative usually looks different:

• nominative: студент
• accusative: студента

через takes the accusative case.

So:

• мережа = network
• accusative singular: мережу

That gives:

• через мережу = through the network / via the network

This is a very useful preposition-case combination to remember:

• через міст = across the bridge
• через дорогу = across the road
• через інтернет = via the internet
• через мережу = through the network

Because бачити takes a direct object, so the pronoun has to be in the accusative.

Here його means it/him in the accusative, and it refers to файл.

So:

• бачить його = sees it

The other forms would mean different things:

• він = he
• йому = to him

So only його works here as the object of бачить.

Also note: for masculine and neuter, його can mean him or it, depending on context. Here it clearly means it, because it refers to файл.

Because на екрані expresses location: on the screen.

After на, Ukrainian can use different cases depending on meaning:

• на + accusative = movement onto/to a surface
  
  • покласти на стіл = put onto the table
• на + locative = location on/at a surface
  
  • лежить на столі = lies on the table

So here:

• на екрані = on the screen (location)
• екрані is the locative singular of екран

The recipient sees the file on the screen, not moving it onto the screen.

одразу means immediately, right away, or at once.

In this sentence:

• одержувач одразу бачить його на екрані
• The recipient immediately sees it on the screen

Its position is fairly flexible, though some placements sound more natural than others:

• одержувач одразу бачить його на екрані
• одержувач бачить його одразу на екрані
• одразу одержувач бачить його на екрані — possible, but less neutral

The version in your sentence is natural and neutral.

Both exist, and both can mean recipient or receiver, but usage can depend on context and style.

• одержувач — common in formal, administrative, postal, and technical contexts
• отримувач — also very common, especially in modern Ukrainian

So in many contexts they are close equivalents.

For example:

• відправник і одержувач
• відправник і отримувач

Both can be understood as sender and recipient.

In technical or official language, одержувач may sound a bit more formal or traditional to some speakers, but both are valid words.

Yes. Ukrainian word order is flexible, though different orders can change the emphasis.

The sentence you have is neutral and natural:

• Коли відправник надсилає файл через мережу, одержувач одразу бачить його на екрані.

Possible variants include:

• Одержувач одразу бачить його на екрані, коли відправник надсилає файл через мережу.
• Коли через мережу відправник надсилає файл, одержувач одразу бачить його на екрані.

These are grammatical, but the original sounds the most straightforward and natural for explanatory or technical prose.

Ukrainian often uses word order to highlight information, but learners should usually start with the most neutral pattern first.

Usually it sounds like a general rule or regular process.

That comes from two things:

1. коли can mean when/whenever
2. надсилає is imperfective present, which often describes repeated or typical actions

So the sentence feels like:

• Whenever the sender sends a file through the network, the recipient immediately sees it on the screen.

If you wanted to emphasize one single completed event, Ukrainian would often use a different structure and possibly a perfective verb, depending on the context.

A few words are worth noticing:

• коли
• відправник
• надсилає
• мережу
• одержувач
• одразу
• екрані

For an English speaker, a few practical points matter:

• Ukrainian и is not the same as English ee; it is a shorter, more central vowel.
• г in Ukrainian is usually softer and breathier than English g.
• є in надсилає often sounds like ye after a vowel.
• Final consonants are generally pronounced clearly.

If you are studying pronunciation closely, it is a good idea to learn each word together with its stress, since stress in Ukrainian is mobile and not always predictable.

Because Ukrainian has no articles like English a/an/the.

So:

• файл can mean a file or the file
• одержувач can mean a recipient, the recipient, or recipient in a general sense

The exact meaning comes from context.

In your sentence, English naturally uses:

• the sender
• a file
• the recipient
• it
• the screen

But Ukrainian expresses all of that without articles. That is completely normal.