Восьмий урок складний.

In the present tense, Ukrainian usually omits the verb to be.

So:

• Восьмий урок складний. = The eighth lesson is difficult.

There is no present-tense є here in normal usage. A literal word-for-word structure is more like:

• eighth lesson difficult

This is completely normal in Ukrainian.

In other tenses, a form of to be does appear:

• Восьмий урок був складний. = The eighth lesson was difficult.
• Восьмий урок буде складний. = The eighth lesson will be difficult.

Восьмий is an ordinal number, but grammatically it behaves like an adjective.

It means eighth, not eight.

Compare:

• вісім = eight
• восьмий = eighth

Because it behaves like an adjective, it changes form to agree with the noun it describes.

Here it describes урок, so it is:

• masculine
• singular
• nominative

That is why the form is восьмий.

Both words are agreeing with урок.

• урок is masculine
• урок is singular
• урок is in the nominative case

So the adjective-like words that go with it also take masculine singular nominative forms:

• восьмий урок
• складний урок

In this sentence, восьмий modifies the noun directly, and складний is a predicate adjective describing the subject.

English does not show this kind of agreement very much, but Ukrainian does it constantly.

Урок is in the nominative case.

That is because it is the subject of the sentence:

• Восьмий урок = the thing being talked about

Since восьмий and складний both relate to урок, they also appear in nominative masculine singular form.

It literally means eighth lesson, but in practice it can correspond to English the eighth lesson or lesson eight, depending on context.

Ukrainian often does not use articles, so the sentence can be understood as:

• The eighth lesson is difficult
• sometimes also Lesson eight is difficult

The exact English wording depends on the situation.

Yes, Ukrainian word order is more flexible than English word order, but the neutral order here is:

• Восьмий урок складний.

This sounds natural and straightforward.

You may also see other orders for emphasis, for example:

• Складний восьмий урок.
• Урок складний.
• Восьмий урок дуже складний.

But not every rearrangement sounds equally neutral. For a learner, Восьмий урок складний is the best basic pattern to remember.

Because складний is an adjective, and it describes the noun урок.

In English, we say:

• The lesson is difficult

Here difficult is also an adjective.

So Ukrainian uses the adjective складний in the same kind of role.

If you wanted an adverb, you would use a different form, for example:

• складно = difficultly / it is difficult

Example:

• Мені складно. = It is difficult for me.

But in your sentence, the thing being described is урок, so the adjective складний is correct.

The tricky part is the cluster сьм.

A useful learner approximation is:

• восьмий ≈ VOSS-my
  with a softened s before m

More carefully:

• the ь does not have its own sound
• it makes the с soft
• then you move into мий

So the soft sign ь affects pronunciation but is not pronounced as a separate vowel or consonant.

If you are just starting, aiming for something like vos-myj with a slightly softened s is a good beginning.

The soft sign ь tells you that the preceding consonant is soft or palatalized.

In восьмий, it softens the с.

So:

• с = hard s
• сь = soft s

The soft sign itself does not add a vowel sound. Its job is to change the consonant before it.

This is a very common feature in Ukrainian spelling and pronunciation.

It can mean both difficult and complex, depending on context.

For example:

• складний урок = a difficult lesson
• складна система = a complex system

So the word has a range similar to English difficult/complex/complicated, and context tells you which translation fits best.

Yes. Because восьмий and складний agree with the noun, they change for gender.

For example:

• masculine: восьмий урок складний
• feminine: восьма лекція складна
• neuter: восьме завдання складне
• plural: восьмі уроки складні

This is a very important pattern in Ukrainian: the ordinal and the adjective both change to match the noun.

Grammatically, learners sometimes build that sentence because they expect a word for is, but in normal Ukrainian this is not the usual way to say it.

The natural sentence is:

• Восьмий урок складний.

Using є here is generally unnecessary and sounds non-native in this kind of simple statement.

So for basic present-tense sentences of this type, it is best to leave is unspoken in Ukrainian.

Like in English, adjectives and ordinal numbers usually come before the noun they modify.

So:

• восьмий урок = eighth lesson
• складний урок = difficult lesson

That is the normal position.

Ukrainian word order is flexible for emphasis, but as a basic rule, put the ordinal before the noun:

• перший урок = first lesson
• другий урок = second lesson
• восьмий урок = eighth lesson