I komšija će doći, ali kasnije.

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Breakdown of I komšija će doći, ali kasnije.

• kasnije: later
• hteti: will
• komšija: male neighbor

Questions & Answers about I komšija će doći, ali kasnije.

Is I here the same as the English pronoun I?

No. In Serbian, i means and, also, or too. It is capitalized here only because it starts the sentence.

What does sentence-initial i add to the sentence?

It shows that komšija is being added to something already mentioned. So the idea is not just that the neighbor will come, but that the neighbor will come as well. If you remove i, the sentence becomes more neutral and loses that also/too nuance.

What is će doći grammatically?

This is the future tense. Serbian forms it with a short auxiliary, here će, plus the infinitive doći. So će doći is the standard way to say will come.

Why is će after komšija, not right after I?

Because će is a clitic, a short unstressed word that normally goes in second position in the clause. The conjunction i does not count as a proper host for it, so će comes after the first stressed element, which is komšija. That is why I komšija će doći is natural, while I će komšija doći is not.