Настільна гра нудна.

In Ukrainian, the verb to be is usually omitted in the present tense.

So:

• Настільна гра нудна. = The board game is boring.

Literally, it is more like:

• Board game boring.

This is completely normal in Ukrainian.
If you want past or future, then forms of бути appear more clearly:

• Настільна гра була нудна. = The board game was boring.
• Настільна гра буде нудна. = The board game will be boring.

Настільна гра means board game.

It is made of:

• настільна = table / tabletop
• гра = game

So the literal idea is something like a tabletop game. This is the normal Ukrainian expression for board game.

Because настільна is an adjective describing гра, and it must agree with the noun.

The noun гра is:

• feminine
• singular
• nominative

So the adjective also takes the feminine singular nominative form:

• masculine: настільний
• feminine: настільна
• neuter: настільне

Since гра is feminine, you say:

• настільна гра

not настільний гра.

For the same reason: нудна describes гра, so it agrees with it in gender and number.

Here нудна means boring and refers to гра:

• гра = feminine singular
• therefore нудна = feminine singular

Compare:

• фільм нудний = the movie is boring
• гра нудна = the game is boring
• завдання нудне = the task is boring

Because гра is the subject of the sentence, so it is in the nominative case.

• гра = nominative singular
• гру = accusative singular

In Настільна гра нудна, the board game is the thing being described, so nominative is correct.

You would use гру when the game is the direct object:

• Я люблю настільну гру. = I like the board game.

It can mean either, depending on context.

Ukrainian has no articles like a or the, so:

• Настільна гра нудна.

could mean:

• The board game is boring
• A board game is boring

Usually the situation tells you which meaning is intended.

Because they do two different jobs:

• настільна is part of the noun phrase настільна гра = board game
• нудна is the predicate adjective: it says what the board game is like

So the structure is:

• [Настільна гра] [нудна].
• [The board game] [is boring].

This is similar to English:

• A big dog is friendly.

where big describes the noun directly, and friendly is the main description in the sentence.

Yes, Ukrainian word order is fairly flexible.

The neutral, straightforward order is:

• Настільна гра нудна.

But other orders are possible for emphasis, for example:

• Нудна настільна гра.

That version can sound more marked or expressive, depending on context. For a beginner, it is best to learn:

• Настільна гра нудна.

as the normal pattern.

In standard Ukrainian, г is usually pronounced more like an English h-like sound, not like the hard English g in go.

So гра sounds closer to hra, not gra.

This is an important difference for English speakers.

Also:

• р is a rolled or tapped r
• гра is one syllable

So try something like hra with a Ukrainian-style r.

Just put не before нудна:

• Настільна гра не нудна. = The board game is not boring.

This is the normal way to negate a predicate adjective.

Grammatically, you may sometimes see є, but in normal present-tense sentences like this, it is usually omitted.

So the natural version is:

• Настільна гра нудна.

Using є here often sounds unnecessary or marked to learners. For everyday Ukrainian, leave it out.

The dictionary form is usually the masculine singular:

• нудний = boring

From that, you get:

• нудний — masculine
• нудна — feminine
• нудне — neuter
• нудні — plural

So in the sentence, нудна is just the feminine form of нудний.

No. The dictionary form is usually:

• настільний

In the sentence, it changes to match гра:

• настільний → masculine
• настільна → feminine
• настільне → neuter
• настільні → plural

So настільна гра is the correctly matched feminine form.

You would use the plural:

• Настільні ігри нудні.

Changes:

• настільна → настільні
• гра → ігри for games
• нудна → нудні

So the whole sentence agrees in the plural.