A wavefunction is basically a function, which contains all the information about a particle. It is the operator you use on it and the operation you perform on it that defines the result that you get out of the operation.
For instance, Hamiltonian H is the operator that one uses to extract the value of energy from the wavefunction using the Schrödinger equation.
A simple and very crude analogy : Basically, it is like a telephone directory. Doing an address search gives the address results, a number search gives a number result and a name search gives a name result.