This is the 544th most frequent Croatian word.
ono
"That" (used for something distant or previously mentioned).
Here, "ono" is used to introduce a relative clause, meaning "that which" or "what".
Ono što želim reći jest da sam sretan.
What I want to say is that I am happy.
In this sentence, "ono" refers to a thing or an event mentioned previously, translating to "that."
Ono je bilo jako zanimljivo.
That was really interesting.
"Ono" here specifies a particular item, acting as a demonstrative pronoun meaning "that."