Message Oracle PLS-00108 - declarative units must be a single variable declaration

ERRORdeclarative units must be a single variable declaration
CAUSEWhile checking a declarative unit (a top-level declare block without the BEGIN...END), PL/SQL found that there was more than one item declared or that the item was not a variable declaration. A table is a common variable declaration at the unit level. To define a TABLE, compile a DECLARE compilation unit, but only one at a time is allowed.
ACTIONDeclare variables in separate declarative units.