This helper that Jesus promised to send is the Holy Spirit, the Third Person of the Trinity. He is just like God the Father and Jesus Christ the Son in His nature, power and purpose. He knows all things. He has all power. He does not have a body but can be everywhere at the same time. Jesus sent the Holy Spirit, just as He promised to do, so that He could live in those who would receive Him. He has come to do for you what Jesus did for His followers.
It is better for you that I go away, because if I do not go, the Helper will not come to you. But if I do go away, then I will send him to you (John 16:7).