"See eye to eye" means to agree with someone or share the same opinion on something. When two or more people in a situation see eye to eye on something, they’ve got a mutual understanding about whatever it is in question. The roots of the idiom “see eye to eye” can be traced back to the Bible. The phrase first appears in the Book of Isaiah (Isaiah 52:8) in the King James Version: “Thy watchmen shall lift up the voice; with the voice together shall they sing: for they shall see eye to eye when the Lord shall bring again Zion.”

Source: Grammarist