Субтитры слишком мелкие.

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

So:

• Субтитры слишком мелкие. = The subtitles are too small.

But in the past or future, forms of быть do appear:

• Субтитры были слишком мелкими. = The subtitles were too small.
• Субтитры будут слишком мелкими. = The subtitles will be too small.

So the missing are is completely normal.

Because субтитры is plural, and the adjective has to agree with it.

Agreement here is:

• субтитр → singular
• субтитры → plural

So:

• Субтитр слишком мелкий. = The subtitle is too small.
• Субтитры слишком мелкие. = The subtitles are too small.

Russian adjectives change form to match the noun in number, and often also in gender and case.

Слишком means too, in the sense of more than is acceptable / more than needed.

So:

• слишком мелкие = too small

This is different from очень:

• очень мелкие = very small
• слишком мелкие = too small

Слишком suggests a problem: the subtitles are so small that they are hard to read.

For text, print, subtitles, handwriting, and similar things, мелкий is often the most natural word.

It usually means something like:

• small-sized
• fine
• tiny in print
• hard to read because of size

So Субтитры слишком мелкие sounds very natural.

Маленькие is more general and often refers to physical size overall. It is not impossible, but for subtitles or font size, мелкие is the better everyday choice.

Compare:

• мелкий шрифт = small print / tiny font
• маленький стол = a small table

Here, субтитры is in the nominative plural, because it is the subject of the sentence.

Мелкие is also in the nominative plural because it agrees with субтитры.

So the basic structure is:

• Субтитры = subject
• слишком = adverb
• мелкие = predicate adjective agreeing with the subject

This is a very common Russian sentence pattern.

The singular is субтитр.

Forms:

• субтитр = one subtitle
• субтитры = subtitles

In normal usage, people often use the plural when talking about subtitles as a feature on a video or movie:

• Где субтитры? = Where are the subtitles?
• Включи субтитры. = Turn on the subtitles.

So the plural in your sentence is exactly what you would expect.

The given order, Субтитры слишком мелкие, is the most neutral and natural.

Russian word order is more flexible than English, but changing it changes emphasis.

For example:

• Субтитры слишком мелкие. = neutral statement
• Слишком мелкие субтитры. = stronger focus on too small
• Мелкие субтитры. = more like small subtitles as a noun phrase, not a full neutral sentence

So for a simple comment like The subtitles are too small, the original word order is best.

A helpful stress guide is:

• субтИтры
• слишкОм
• мЕлкие

A rough English-style approximation would be:

• soob-TEE-try slish-KOM MYEL-kee-ye

A few pronunciation notes:

• тры in субтитры does not have a direct English equivalent, so listen and repeat if possible.
• е in мелкие sounds like ye after a soft consonant.
• The final -ие in мелкие is pronounced clearly, not reduced to one syllable.

Yes, you can, because мелки is the short form of the adjective мелкий.

So both are possible:

• Субтитры слишком мелкие.
• Субтитры слишком мелки.

However, мелкие sounds more neutral and everyday to many learners and in many contexts. The short form мелки can sound a bit more formal, literary, or concise.

As a learner, Субтитры слишком мелкие is the safer choice.

Russian has no articles, so there is no direct equivalent of a, an, or the.

Whether субтитры means:

• subtitles
• the subtitles
• sometimes even some subtitles

depends on context.

In this sentence, the context makes it clear that we mean the subtitles currently being discussed or seen on the screen, so English naturally uses the even though Russian does not.