Learn Croatian: Konačno je dječak zaspao. - Finally, the boy fell asleep.

In the Croatian past tense, the helper verb (je) is a special "weak" word called an enclitic. These weak words must always take the second position in the sentence. Because the adverb Konačno (Finally) takes the first position, je has to lock in right behind it, separating it from the main action word zaspao.

If the past tense uses an "l-participle", why does zaspao end in -o?

For masculine subjects like dječak (boy), the past tense word historically ended in -l, but over time that sound changed to an -o at the end of most verbs. So, instead of "zaspal", we say zaspao. If the subject were feminine, the "l" sound stays and adds an "a", becoming zaspala.

Could we change the word order and start the sentence with Dječak?

Yes, you can! If you put the subject first, the sentence becomes Dječak je konačno zaspao. Notice how the weak word je stays firmly in the second position, right after the first word (Dječak). The meaning stays exactly the same, it just puts slightly less emphasis on the word "Finally".

What if we drop the word konačno to just say "The boy fell asleep"?

Then the sentence would simply be Dječak je zaspao. The helper verb je takes the second spot after the first word. You could also say Zaspao je dječak, but the helper verb je must always stay in that second spot, no matter what word starts the sentence!