3 Nephi 28:10-11

"...and ye shall be even as I am, and I am even as the Father; and the Father and I are one;

And the Holy Ghost beareth record of the Father and me; and the Father giveth the Holy Ghost unto the children of men, because of me."

These verses explain the relationships of the Godhead. The Father and the Son are one, meaning that they are one in purpose. The Holy Ghost ministers unto men because of the Father and the Son.