Važno je da uvek nosiš svoj pasoš sa sobom.

Because Važno je... is an impersonal structure meaning It is important....

In Serbian, adjectives in this kind of sentence usually appear in the neuter singular form, so:

• važan = masculine
• važna = feminine
• važno = neuter

So Važno je da... is the normal way to say It is important that...

Also, je is a clitic, so Važno je is the natural order, not Je važno.

Serbian very often uses da + present tense where English would use an infinitive.

So:

• Važno je da uvek nosiš... = literally It is important that you always carry...
• natural English: It is important to always carry...

A version with the infinitive, such as Važno je uvek nositi..., can also exist, but da + present is very common and natural in Serbian.

Nosiš is the 2nd person singular present tense of nositi, meaning to carry / to wear / to take with you depending on context.

Here it means or .