Taj padež mi je još težak, ali njegovo značenje mi je sada jasnije.

It has two main clauses joined by ali:

• Taj padež mi je još težak
• ali njegovo značenje mi je sada jasnije

In both clauses, the pattern is basically subject + clitics + predicate.
So:

• taj padež = subject
• mi je = clitic pronoun + auxiliary
• još težak = predicate adjective phrase

and then:

• njegovo značenje = subject
• mi je = again, clitic pronoun + auxiliary
• sada jasnije = predicate adjective phrase

The sentence is contrasting two ideas: one thing is still difficult, but another aspect of it has become clearer.

Taj padež is in the nominative singular.

You can tell because it is the subject of the first clause: it is the thing being described as težak.
Both words match each other:

• taj = masculine singular nominative
• padež = masculine singular nominative

Croatian adjectives, demonstratives, and nouns agree in gender, number, and case, so taj padež works as one nominative subject phrase.

Mi here means to me and is the dative singular form of ja.

It appears twice because each clause has its own personal perspective:

• Taj padež mi je još težak = that case is still difficult for me
• njegovo značenje mi je sada jasnije = its meaning is now clearer to me

This is very natural in Croatian. The dative here marks the experiencer: the person to whom something is difficult or clear.

Because both mi and je are clitics, and Croatian has strong rules about clitic order.

In a clitic cluster, mi normally comes before je:

• mi je

These clitics also tend to appear in second position in the clause, after the first stressed word or phrase. So you get:

• Taj padež | mi je | još težak
• Njegovo značenje | mi je | sada jasnije

This is one of the most important word-order patterns in Croatian.

Here još means still.

So još težak means still difficult. It shows that the situation continues from before up to now.

Be careful: još can also mean more or another in other contexts. But in this sentence, with an adjective and the time contrast in the sentence, still is the right sense.

Because it has to agree with padež, which is masculine singular nominative.

So the adjective also appears in the masculine singular nominative form:

• padež → masculine singular
• težak → masculine singular

If the noun were feminine or neuter, the form would change:

• teška
• teško

Agreement is one of the core features of Croatian grammar.

Yes. Težak literally means heavy, but like English hard or difficult, it is also used figuratively.

So:

• težak kovčeg = a heavy suitcase
• težak zadatak = a difficult task
• težak padež = a difficult grammatical case

This figurative use is completely normal in Croatian.

Njegovo refers back to padež, so its meaning is basically its.

The important point is this: Croatian possessive forms like njegov / njegova / njegovo agree with the thing possessed, not with the possessor.

Here, the thing possessed is značenje, and značenje is neuter singular, so the possessive must also be neuter singular:

• njegovo značenje

Even though the owner is padež and padež is masculine, the form is chosen by značenje, not by padež.

Because značenje is a neuter singular noun, and the predicate adjective must agree with it.

So:

• značenje = neuter singular
• jasnije = neuter singular comparative form

This is the same agreement principle you saw with padež and težak.
Croatian predicate adjectives match the subject in gender, number, and case.

Jasnije means clearer or more clear. It is the comparative form of jasno / jasan.

The comparison is implied, not stated explicitly. The sentence means that the meaning is clearer now than before.

Croatian often does this, just like English:

• It’s clearer now.
• Sada je jasnije.

You do not always need to say than before or use nego if the comparison is obvious from context.

Sada means now.

It emphasizes a change over time:

• the case is still difficult
• but its meaning is now clearer

So još and sada work together nicely:

• još = the difficulty continues
• sada = understanding has improved by this point

That contrast is one of the key ideas of the sentence.

Yes, Croatian word order is fairly flexible, but not completely free.

For example, you could also hear:

• Taj mi je padež još težak
• Njegovo mi je značenje sada jasnije

These are possible because Croatian can move things around for emphasis or rhythm.
However, the clitics mi je still usually stay together and follow the normal clitic-placement rules.

The original sentence sounds natural and neutral.

Yes, in some contexts it could be omitted if it is already obvious who is experiencing the difficulty or clarity.

For example:

• Taj padež je još težak, ali njegovo značenje je sada jasnije.

That is grammatically fine, but it sounds a bit less personal.
Including mi makes the sentence clearly about my experience of learning or understanding.

So the version with mi is very natural in learner-type contexts.

Because Croatian does not have articles.

Instead, definiteness is usually understood from:

• context
• word order
• demonstratives such as ovaj, taj, onaj

Here taj already helps make padež specific: not just any case, but that particular case.
So Croatian expresses that idea without needing a separate word like the.

Because ali joins two independent clauses, and Croatian normally uses a comma before it in this kind of sentence.

So the comma separates:

• Taj padež mi je još težak
• ali njegovo značenje mi je sada jasnije

This is similar to English punctuation before but in many cases.