Ganesha is the formless Divinity - encapsulated in a magnificent form, for the benefit of the devotee.

Meaning of Ganesh
Gan means group. The universe is a group of atoms and different energies.

This universe would be in chaos if there was no supreme law governing these diverse groups of entities. The Bhagvan of all these groups of atoms and energies is Ganesha. He is the supreme consciousness that pervades all and brings order in this universe.

Bhagvan Ganesha is
Achintya - beyond thought
Avyakta - beyond expression
Ananta - eternal
The essence of Ganesha is brought out beautifully by Adi Shankara.

Though Ganesha is worshiped as the elephant-headed God, the form (suaroop) is just to symbolize the qualities of the Divine (parabrahma roopa). He is, Ajam Nirvikalpam Niraakaaramekam. This means Ganesha is Ajam (unborn), he is Nirvikalpa (attributeless),he is Nirakar (formless)

and he symbolizes the consciousness which is omnipresent. Ganesha is the same energy which is the reason for this universe. It is the energy from which everything manifests and into which everything will dissolve.

Credit.... @ancient_bharath