It is common to distinguish the ‘is’ of identity (Mount Everest is Chomolungma); the ‘is’ of predication (Jones is a bore); and the ‘is’ of existence (there is a life after death). In the treatment of propositions of this complexity in the predicate calculus there is no symbolism common to these three, and the theory of why a natural language such as English finds a common element is not at all certain. It seems quite possible to present the same information without any such common element: Jones bores; life after death exists.
Philosophy dictionary. Academic. 2011.