Svi ponekad griješimo, ali to nije problem.

Svi means all / everyone here.

Grammatically, svi is the nominative plural form usually used for:

• a mixed group of people
• a general statement about people in general

So Svi ponekad griješimo means We all sometimes make mistakes or Everyone sometimes makes mistakes.

Why not sve?

• sve can mean all things / everything
• it can also be a feminine plural form in some contexts

But for a general everyone / all of us meaning, svi is the normal choice.

It can, but it usually doesn’t need to.

In Croatian, the verb ending already tells you the subject:

• griješim = I make mistakes
• griješiš = you make mistakes
• griješimo = we make mistakes

Because -mo already means we, the pronoun mi is often omitted.

So:

• Svi ponekad griješimo = natural, neutral
• Mi svi ponekad griješimo = possible, but more emphatic, like we all specifically

Croatian often drops subject pronouns unless they are needed for contrast or emphasis.

Griješimo is the 1st person plural present tense of griješiti.

So:

• infinitive: griješiti = to make mistakes / to be mistaken
• present: griješimo = we make mistakes / we are making mistakes

Breakdown:

• griješ- = verb stem
• -imo = ending for we

A useful note: in some contexts griješiti can also mean to sin, but in everyday sentences like this one it usually means to make mistakes.

This is about aspect, which is very important in Croatian.

• griješiti = imperfective
  Used for repeated, habitual, or general actions
• pogriješiti = perfective
  Used for one completed mistake or a specific instance

This sentence is making a general truth:

• Svi ponekad griješimo = We all make mistakes sometimes

That is why the imperfective griješimo fits best.

Compare:

• Ponekad griješimo. = Sometimes we make mistakes.
• Opet smo pogriješili. = We made a mistake again.

Ponekad means sometimes.

Yes, Croatian word order is fairly flexible, so you can move it around:

• Svi ponekad griješimo.
• Ponekad svi griješimo.
• Svi griješimo ponekad.

All of these are possible, but they may sound slightly different in emphasis.

The original version, Svi ponekad griješimo, is very natural and neutral.

Here to means that / it.

It refers to the whole previous idea:

• the fact that we sometimes make mistakes

So:

• ali to nije problem = but that is not a problem
• very natural English equivalent: but that’s not a problem

You could sometimes say just ali nije problem, but to makes the reference clearer and sounds very natural here.

Historically it comes from negation, but in standard Croatian you treat nije as the normal negative form of je (is).

So:

• je = is
• nije = is not

This is part of an irregular set:

• nisam = I am not
• nisi = you are not
• nije = he/she/it is not
• nismo = we are not
• niste = you are not
• nisu = they are not

So in standard Croatian, you should learn nije as a fixed form, not as two separate words.

Because Croatian has no articles.

English uses:

• a problem
• the problem

Croatian simply says:

• problem

So nije problem can mean:

• is not a problem
• is not the problem

The exact meaning comes from context.

In this sentence, English normally translates it as not a problem.

Because ali means but, and it joins two clauses:

• Svi ponekad griješimo
• ali to nije problem

In Croatian, a comma is normally used before ali when it connects clauses, just like English often uses a comma before but.

So the punctuation here is standard and expected.

Yes. Croatian allows more word-order flexibility than English.

For example, these are all possible:

• Svi ponekad griješimo, ali to nije problem.
• Ponekad svi griješimo, ali to nije problem.
• Svi griješimo ponekad, ali to nije problem.

They all mean roughly the same thing, but the emphasis shifts a little.

The original sentence sounds the most neutral and natural for a general statement.