Этот лак держится дольше, чем тот.

Here it is the verb держаться, not держать.

• держать = to hold something
• держаться = to stay on, remain, last, hold up

So in this sentence, Этот лак держится дольше means something like:

• This polish lasts longer
• This polish stays on longer
• This varnish holds up longer

With products like nail polish, paint, coating, or hair spray, держаться often means to last well / to stay in place for a long time.

The -ся ending marks a reflexive verb. But in Russian, reflexive verbs do not always mean a literal oneself action.

In this case, держаться is just the normal dictionary form for the meaning to last / to stay on / to remain.

So you should learn these as two different verbs:

• держать = to hold
• держаться = to hold on / stay / last

This is very common in Russian: adding -ся can create a verb with a related but different meaning.

Because дольше is describing how long the action lasts, not describing the noun лак itself.

• долгий is an adjective: long
• дольше is the comparative form of долго: longer

So:

• лак = the thing
• держится = lasts/stays on
• дольше = for a longer time

In English, we also usually use an adverb-like idea here: lasts longer, not is longer.

Дольше is the comparative form of долго (for a long time / long in an adverb sense).

So:

• долго = a long time
• дольше = longer

This is an irregular-looking comparative, so it is best learned as a set form.

Example:

• Он ждал долго. = He waited a long time.
• Он ждал дольше меня. = He waited longer than me.

Чем means than in comparisons.

So:

• дольше, чем тот = longer than that one

This is one of the standard ways to make comparisons in Russian:

• лучше, чем... = better than...
• быстрее, чем... = faster than...
• дольше, чем... = longer than...

Тот means that one here.

The full idea is:

• Этот лак держится дольше, чем тот лак.

But Russian often leaves out the repeated noun when it is obvious. So тот stands alone and means:

• that one
• literally, that (polish/varnish)

This is very natural in both Russian and English.

Because Russian often avoids repeating a noun if the meaning is already clear.

So these are equivalent in meaning:

• Этот лак держится дольше, чем тот.
• Этот лак держится дольше, чем тот лак.

The shorter version sounds more natural in most situations.

They are in the nominative case.

• этот лак = nominative singular masculine
• тот = nominative singular masculine, standing in for тот лак

Why nominative? Because both refer to the thing being compared:

• This polish lasts longer than that one.

The second part is really a shortened comparison where тот stands for the subject of the omitted clause.

Not always. Лак can mean different kinds of varnish, lacquer, polish, coating, depending on context.

For example, it can refer to:

• nail polish
• wood varnish
• hair spray in some contexts, though лак для волос is more specific

So the exact English translation depends on the situation. If the learner has already been shown the meaning, then the sentence probably refers to the intended kind of лак from context.

Yes, Russian word order is flexible, though the original sentence is the most neutral and natural.

The basic version:

• Этот лак держится дольше, чем тот.

You may also see variations for emphasis, but beginners should stick to the standard order above.

Russian often changes word order to highlight contrast or focus, but the meaning usually stays the same because the grammar endings help show each word’s role.

Grammatically, something like that might be understood, but it sounds unnatural. Russian strongly prefers the simple comparative:

• Этот лак держится дольше, чем тот.

In general, with common comparisons, Russian usually uses forms like:

• лучше
• хуже
• быстрее
• дольше

rather than heavier constructions.

Yes, держится is present tense, 3rd person singular.

But in Russian, just like in English, the present tense can express a general truth or usual property:

• This polish lasts longer than that one.

It does not have to mean only right now at this exact moment. It can mean in general / typically / when used.

A helpful approximation is:

• Этот = EH-tət
• лак = lak
• держится = DYER-zhit-sya
• дольше = DOL-she
• чем = chem
• тот = tot

A few useful stress notes:

• де́ржится? Actually the stress is де́ржится? No — in standard Russian it is де́ржится?
  The normal stress is де́ржится?
  Learners should be careful here because stress matters.

The most important pronunciation point for beginners is that -тся / -ться is pronounced roughly like -tsa.

You can, if it helps you understand the structure.

The full logical idea is something like:

• Этот лак держится дольше, чем тот [держится].

Russian often omits repeated words, especially verbs and nouns, when they are obvious from context.

So yes, mentally supplying the missing verb can help at first, but in normal Russian the shorter version is preferred.