Inače učim hrvatski navečer, ali danas učim ujutro.

Here inače means usually, normally, or as a rule.

So in this sentence, it contrasts your normal routine with what is happening today:

• Inače = normally / usually
• danas = today

A very natural English translation is Usually I study Croatian in the evening, but today I study in the morning.

Croatian often drops subject pronouns when they are not needed.

The verb učim already tells you the subject is I, because it is the 1st person singular form of učiti.

So:

• učim = I study / I am studying / I learn

You could say Ja učim..., but ja is usually only added for emphasis, contrast, or clarity.

Učim is the present tense, 1st person singular, of the verb učiti.

Base verb:

• učiti = to study / to learn

Present tense:

• ja učim = I study / I am studying

In Croatian, the present tense can often cover both:

• I study
• I am studying

The exact meaning depends on context.

Because there are two clauses, and each clause has its own verb:

• Inače učim hrvatski navečer
• ali danas učim ujutro

Croatian usually keeps the verb in both parts when the contrast is clear and complete. Repeating učim sounds natural.

If you removed the second učim, the sentence would feel more elliptical and less standard for a learner.

In Croatian, when talking about a language, the adjective is often used by itself:

• učim hrvatski = I’m learning Croatian
• literally: I’m learning Croatian [language]

The full form is:

• hrvatski jezik = Croatian language

But in everyday speech, people usually just say:

• engleski = English
• njemački = German
• hrvatski = Croatian

So učim hrvatski is completely normal.

Yes, this form matches what the verb učiti normally takes when you mean to study/learn a subject or language.

Here hrvatski is functioning like the object of the verb:

• učim hrvatski
• učim matematiku
• učim povijest

With languages, Croatian commonly uses the adjective form as a noun, and here that form is hrvatski.

So this is the normal form after učiti when you mean learn Croatian.

They are adverbs of time:

• navečer = in the evening
• ujutro = in the morning

They answer the question when?

So:

• učim navečer = I study in the evening
• učim ujutro = I study in the morning

These are very common time expressions in Croatian.

Because in these meanings they function as fixed adverbs, and they are normally written as one word:

• ujutro
• navečer

English speakers often expect something like in the morning with a separate preposition, but Croatian often uses these single-word adverbs instead.

So it is not:

• u jutro for this meaning
• na večer for this meaning

The standard forms here are:

• ujutro
• navečer

Croatian word order is fairly flexible. Danas is placed early here to highlight the contrast with inače:

• Inače ... = usually ...
• danas ... = today ...

That makes the sentence flow very naturally.

Other word orders may also be possible, depending on emphasis, for example:

• Ali učim danas ujutro
• Ali danas ujutro učim

But the original sentence sounds very natural and balanced.

Ali means but. It introduces a clear contrast:

• usually in the evening
• but today in the morning

So ali is the natural choice.

Croatian also has a, which can sometimes mean and, while, or but, but ali is stronger and more direct for this kind of contrast.

Yes, very often you can.

• obično = usually
• inače = normally / otherwise / as a rule / in general

In this sentence, both can work:

• Obično učim hrvatski navečer, ali danas učim ujutro.
• Inače učim hrvatski navečer, ali danas učim ujutro.

The difference is small here, but inače can feel a bit broader, like normally or under normal circumstances.

Because ali joins two clauses, and in standard Croatian punctuation, a comma is normally used before it.

So:

• Inače učim hrvatski navečer, ali danas učim ujutro.

That comma is standard and expected.

It can mean either, depending on context.

In this sentence:

• Inače učim... clearly means a habit: I usually study...
• danas učim... refers to today’s situation

Croatian does not make the same strict grammatical distinction that English does between:

• I study
• I am studying

So the Croatian present tense often covers both ideas, and context tells you which one is meant.