What is and authorization object

An authorization object is a collection of fields. Each field can have many values.
For example S_TABU_DIS has two fields.

Authorization Field	Long Text
DICBERCLS	Authorization group
ACTVT	Activity

This authorization object is checked when tcode se16 (table display) is executed.

ACTVT is the activity one can do in that tcode. and DICBERCLS is the authorization group for which the ACTVT is valid.

if you have values ACTVT as 3 (display ) and DICBERCLS is "par" you can see all the tables which are included in authorization group par. and if you have ACTVT as 2 (change) then you can edit the tables in authorization group par.