Answer
In Hindu Dharma, God is fundamentally formless (nirakara). The formless God is called Brahman. When Brahman (the formless God) creates the universe, He also assumes saakar (with-form) aspects — bodies with shape and colour — for the work of creation, sustenance, and dissolution. As Brahma, He creates; as Vishnu, He sustains; as Shiva, He dissolves.
Furthermore, Hindu Dharma teaches that the Para-Brahman Parameshwara also takes birth in human form from time to time — to restore the balance between dharma and adharma, and for the joy of His devotees. Thus He took human avataras as Shri Rama and Shri Krishna.
So ultimately, it is the One God who is encountered in many forms — and this naturally invites the final question of this lesson: can we actually see and hear God?