Upisaću početni kurs.

Upisaću is the 1st person singular future form of upisati, meaning I will enroll / I will sign up.

It is formed from:

• upisati = the infinitive
• ću = the clitic future form of hteti for I will

When ću comes after an infinitive ending in -ti, Serbian usually drops -ti and attaches ću to the verb:

upisati + ću → upisaću

A more expanded version of the same idea is:

Ja ću upisati početni kurs.

Both mean the same thing.

Because Serbian often leaves out subject pronouns when the verb already shows the person clearly.

In upisaću, the ending already tells you the subject is I. So ja is not necessary.

• Upisaću početni kurs. = neutral, natural
• Ja ću upisati početni kurs. = also correct, but ja adds emphasis, contrast, or clarity

This is very common in Serbian.

Because upisati is a perfective verb, and perfective verbs are very common for a single completed future action.

Here, the speaker means one whole action:

I will enroll in the course.

That is why upisati fits well.

An imperfective form would suggest something more like:

• an ongoing process
• repetition
• habit
• a more open-ended action

So for a simple plan to complete the act of enrolling, upisati is the natural choice.

Because Serbian does not always match English word-for-word.

With upisati, Serbian can use the course as a direct object:

• upisati kurs

So Upisaću početni kurs is natural Serbian.

You may also hear:

• Upisaću se na početni kurs.

That version uses the reflexive se and the preposition na. It is also natural. The difference is mostly in structure, not basic meaning.

So:

• upisati kurs = enroll in the course
• upisati se na kurs = enroll oneself in/on the course

Both are used.

Here, početni kurs is in the accusative, because it is the direct object of upisaću.

But the forms look the same as nominative because of the type of noun involved:

• kurs is a masculine inanimate noun
• masculine inanimate nouns usually have the same form in nominative and accusative singular

So:

• nominative: početni kurs
• accusative: početni kurs

The adjective početni agrees with kurs, so it stays in the matching masculine singular form as well.

Početni means something like:

• introductory
• beginner
• basic
• initial

In the phrase početni kurs, the most natural English rendering is often:

• introductory course
• beginner course

The exact English choice depends on context, but in Serbian početni is the normal adjective for the starting level.

Yes, Upisaću početni kurs is perfectly normal.

Serbian word order is more flexible than English word order. Since the subject I is omitted, the sentence naturally begins with the verb.

You can also say:

• Ja ću upisati početni kurs.

That version is also correct, but it sounds a bit more explicit because ja is stated.

So both are fine:

• Upisaću početni kurs.
• Ja ću upisati početni kurs.

The first one is very natural in everyday Serbian.

They are similar, but not always identical.

• Upisaću kurs
  This often means I will enroll in / register for the course. It treats kurs as the direct object.

• Upisaću se na kurs
  This explicitly means I will enroll myself in the course. It is very close in meaning to the first version.

• Prijaviću se na kurs
  This usually means I will sign up for / apply for the course. It can sound slightly less final than upisati, depending on context.

So if you want the clearest idea of actual enrollment, upisati is often the stronger choice.

The tricky sound is ć.

It is a soft consonant, softer than č. English does not have an exact equivalent, but you can approximate ću as something between:

• tyoo
• a very soft choo

So upisaću can be broken into syllables as:

u-pi-sa-ću

You do not need a perfect native pronunciation right away; the main thing is to keep ć softer than č.