What is the meaning of "predicate" in this definition?
I have trouble understanding the article on existence in this Philosophy dictionary.
Instantiation in reality, or actual being. Kant pointed out that existence is not a predicate.
What is the meaning of predicate in other words, put simply?
is there any eBook or Book for Philosophy for dummies? or dictionary for other foreign languages.
Predicate is a unary Boolean function. For example, Even(n) is a predicate that takes a number n as its argument and returns true just in case n is even.
This isn't really a "look it up in the dictionary" kind of question, it's a context specific technical term.
To expand a little on Hunan's comment, predicates in the form he describes are the basis of First Order Logic(FOL), which is one of the most widely accepted formal systems today. Philosophy which tries to boil down everything into predicates makes it easier to draw conclusions from that philosophy using FOL.
The context is the use of existence as a predicate in the ontological argument for God's existence. There are several possible interpretations, the simplest being that existence can not be added to a list of properties and the result handled as if it defines something, see http://philosophy.stackexchange.com/questions/24484/is-there-a-suppressed-premise-in-anselms-ontological-argument/24487#24487 and the paper linked there.
A predicate, from the Latin praedicare, which is itself a translation of Aristotle's κατηγορῆται, is something that is 'said of' something else. Thus in 'Socrates is bald', the predicate 'bald' is said of Socrates. To say that existence is not a predicate means that existence is not really said of any individual, i.e. is not a property of an individual in the way that being bald, being white etc are properties.
If it were a predicate, then 'Socrates does not exist' would be saying of some individual that he lacks some property, namely existence. But that is absurd: how can there be some individual such that there is no such individual? "Blue buttercups do not exist" is not saying that there are such things as non-existent blue buttercups. Rather, it is saying that no buttercups are blue.