Нашийник на столі.

In Ukrainian, the present-tense verb to be is usually omitted in simple sentences like this.

So:

• Нашийник на столі. = The collar is on the table.

Literally, Ukrainian often just says Collar on table where English requires is.

If you wanted past or future, then forms of бути (to be) would appear:

• Нашийник був на столі. = The collar was on the table.
• Нашийник буде на столі. = The collar will be on the table.

Because на here shows location, and after на when it means on / in a place, Ukrainian normally uses the locative case.

• dictionary form: стіл = table
• locative singular: на столі = on the table

So the pattern is:

• стіл → на столі

This is very common:

• на підлозі = on the floor
• на полиці = on the shelf
• на столі = on the table

Here на means on.

So:

• на столі = on the table

A useful thing to know is that на can be used with different cases depending on meaning:

• location → usually locative
  
  • на столі = on the table
• movement toward a surface/place → often accusative
  
  • на стіл = onto the table

So compare:

• Нашийник на столі. = The collar is on the table.
• Поклади нашийник на стіл. = Put the collar onto the table.

Because нашийник is the main noun of the sentence, and here it is in the nominative singular, which is the basic dictionary form.

• нашийник = collar

In this sentence, it is the thing being talked about:

• Нашийник на столі. = The collar is on the table.

So:

• нашийник = nominative
• столі = locative after на

Usually нашийник means a collar worn around the neck, especially an animal collar such as a dog’s collar.

So in many contexts, learners will understand it as:

• pet collar
• dog collar
• neck collar

It does not usually mean the collar of a shirt. For clothing, Ukrainian normally uses other words, such as комір.

So:

• нашийник = an animal/neck collar
• комір = shirt collar / coat collar

Yes. Ukrainian word order is fairly flexible, and changing it often changes the focus rather than the basic meaning.

For example:

• Нашийник на столі.
  Neutral: The collar is on the table.

• На столі нашийник.
  Puts more attention on where it is: On the table, there is a collar / The collar is on the table.

So the original sentence is a very natural neutral order, but other orders are possible.

Because Ukrainian has no articles.

So нашийник can mean:

• a collar
• the collar

And на столі can mean:

• on a table
• on the table

The exact meaning depends on context.

That means Нашийник на столі. could be interpreted in English as either:

• A collar is on the table.
• The collar is on the table.

Usually the situation tells you which one is meant.

Yes, normally на столі means on the surface of the table.

If you wanted a different meaning, Ukrainian would usually use a different phrase:

• біля столу = near the table
• під столом = under the table
• за столом = at the table / seated at the table

So на столі is quite specific: something is resting on the table.

Yes, absolutely. It is a complete and natural Ukrainian sentence.

Ukrainian often allows short, simple statements like this, especially when the meaning is clear:

• Книга на полиці. = The book is on the shelf.
• Ключі в сумці. = The keys are in the bag.
• Нашийник на столі. = The collar is on the table.

This kind of sentence is very common in both speech and writing.