This is the 304th most frequent Slovenian word.
ostali
"Remaining" or "the rest."
In this sentence, 'ostali' is a noun subject referring to 'the others'.
Ostali bodo prišli kasneje, ko se jim konča delo.
The others will come later, after they finish their work.
Here, 'ostali' is a verb in past participle form, meaning 'stayed'.
Na sestanku so ostali tisti, ki so želeli razpravljati dalje.
At the meeting, those who wanted to continue the discussion stayed.
Here, 'ostali' is used as an adjective meaning 'the other'.