Orbital wave function ψ is a mathematical function for an atomic orbital.
The square of the wave function, ψ2 is called probability density and is always positive.
Its value defines the probability of finding the electron around nucleus.
Hamiltonian operator H is an operator corresponding to the total energy of the system as Hψ=Eψ
Principal quantum number defines the shell and majorly governs the energy and size of the orbital. It is one of the solution obtained from ψ.