Per_all_assignments_f - column POSITION_ID tells information about position that the person hold. Query this table using PERSON_ID of an individual
In Per_positions - query the column NAME by passing Postion_ID that you get from Per_all_assignments_f
Hope this info will be useful to you.
Some additional information on the tables used...
HR_ALL_POSITIONS_F is a datetracked tables holding details of the position definition.
The actual segment values are held in table PER_POSITION_DEFINITIONS which has a column for each segment value.
The 2 tables are joined with column POSITION_DEFINITION_ID.