Samopouzdanje raste s iskustvom.

• samopouzdanje = self-confidence
• raste = grows / increases
• s iskustvom = with experience

So grammatically:

• samopouzdanje is the subject
• raste is the verb
• s iskustvom is a prepositional phrase showing what this growth is connected with

A very literal gloss would be: Self-confidence grows with experience.

Because it is the subject of the sentence, so it is in the nominative case.

Samopouzdanje is a neuter singular noun. Many Croatian nouns ending in -nje are neuter, and in the nominative singular they often look exactly like this.

Here, the sentence is about self-confidence as one general thing, so the basic dictionary form is used.

Raste is the 3rd person singular present tense of rasti (to grow).

It is singular because the subject, samopouzdanje, is singular.

So the agreement is:

• samopouzdanje = singular
• raste = singular verb form

If the subject were plural, the verb would also change. For example:

• Biljke rastu. = Plants grow.

But here:

• Samopouzdanje raste. = Self-confidence grows.

Because after s in this sentence, Croatian uses the instrumental case.

The noun is:

• nominative: iskustvo = experience
• instrumental: iskustvom = with experience

So:

• s iskustvom = with experience

This is a very common pattern:

• s prijateljem = with a friend
• s vremenom = with time
• s praksom = with practice

Here s means with.

In this sentence, it expresses an idea like as experience comes or together with experience. It links the increase in self-confidence to the presence or accumulation of experience.

So s iskustvom does not mean physical accompaniment only. It can also express a more abstract relationship:

• S godinama dolazi mudrost. = Wisdom comes with age.
• Samopouzdanje raste s iskustvom. = Self-confidence grows with experience.

The basic form is s.

Croatian often uses sa instead of s when pronunciation would otherwise be awkward, especially before words beginning with certain consonants such as s, š, z, ž, or difficult consonant clusters.

For example:

• sa sestrom
• sa školom

But before iskustvom, plain s sounds natural and standard:

• s iskustvom

So s iskustvom is the normal choice here.

It can mean both.

The basic verb rasti literally means to grow, as plants or children do. But it is also very commonly used metaphorically for things that increase over time:

• Cijene rastu. = Prices are rising.
• Napetost raste. = The tension is growing.
• Samopouzdanje raste. = Self-confidence grows / increases.

So in this sentence, raste is a very natural verb.

It normally means experience in general.

The singular noun iskustvo often works like English experience when we mean accumulated knowledge or practice, not one individual event.

So:

• iskustvo = experience in the broad sense
• jedno iskustvo = one experience if you want to mean one particular event

In this sentence, s iskustvom means as a person gains experience over time.

It is mainly a general truth.

Croatian, like English, often uses the present tense for statements that are generally true:

• Voda vrije na 100 stupnjeva. = Water boils at 100 degrees.
• Samopouzdanje raste s iskustvom. = Self-confidence grows with experience.

So the sentence is not just describing one moment right now. It states a general pattern.

Yes. Croatian word order is fairly flexible.

The most neutral version here is:

• Samopouzdanje raste s iskustvom.

But other orders are possible for emphasis or style, for example:

• S iskustvom raste samopouzdanje.
• Raste samopouzdanje s iskustvom.

These still mean roughly the same thing, but the emphasis shifts a little. The original order is the most straightforward and natural for a learner to use.

Yes, it is the standard and very common word.

You may also encounter expressions built around pouzdanje or phrases like vjera u sebe depending on context, but samopouzdanje is the normal direct equivalent of self-confidence.

So this sentence sounds natural and idiomatic.

Usually, for this meaning, s iskustvom is the most natural choice.

Bare instrumental without a preposition does exist in Croatian, but it often has a slightly different feel, sometimes more like by means of or through. In this sentence, s iskustvom clearly gives the meaning with experience / as experience is gained.

So for a learner, the safest and best version is:

• Samopouzdanje raste s iskustvom.

A simple approximate pronunciation is:

sah-moh-poh-ooz-DAH-nyeh RAH-steh s ee-SKOOST-vom

A few useful notes:

• j in Croatian sounds like English y
• nj is a single sound, like the ny in canyon
• r is rolled or tapped
• stress can vary by dialect and teaching style, but this approximation will be understood well

So samopouzdanje ends roughly like -dah-nyeh, not like English j.