Yes, staff is a noun, 'staff' is a singular, common, concrete noun; a word for the people who work for a particular company or organization; employees as a group; a word for the set of lines on which music is written; a word for a long stick used for making walking easier on rough terrain; a stick carried by officials on formal occasions; a flagpole.
The word staff is also a verb: staff, staffs, staffing, staffed; a word for the act of providing workers or to serve as a worker.
The noun 'staff' is a standard collective noun for a staff of employees.
The collective noun 'staff' is used for a staff of workers or a staff of employees.
The collective noun 'staff' is used for a staff of workers or a staff of employees.
The noun staff is a singular, common, collective noun.
The noun staff is a singular, common, collective noun.
Collective noun
The word "staff" itself is a collective noun: E.g. (American English) "The staff is on break." (British English) "The staff are on break."
Collective noun
The plural form for of the noun chief-of-staff is chiefs-of-staff.
The plural form for of the noun chief-of-staff is chiefs-of-staff.
Staff of teachers
The plural form for of the noun chief-of-staff is chiefs-of-staff.