Please use the Search facility at the top of the page next to the CiteHR logo.
There is plenty of information about Form O there posted previously by members of CiteHR.
I do not know what the form is, but suspect that if it is a printed form issued by a government authority, it will be a matter of filling in details about staff members under a range of headings. So read the form and simply fill in the details asked for. Best not to overthink these things.