In every sentence there is bound to be predication, without which there would be no sentence. In a usual two-member sentence the predication is between the subject and the predicate. In most sentences this is the only predication they contain. However, there are also sentences which contain one more predication, which is not between the subject and the predicate of the sentence. This predication may conveniently be termed secondary predication.
A secondary predicate is a (mostly adjectival) predicative expression that conveys information about the subject but is not the main predicate of the clause. This structure may be analysed in many different ways.
These may be resultative, as in (1) and (2) or descriptive as in (3).
(1) She painted the town red
(2) The film left me cold
(3) Susan walked around naked.