From Louis Berkhof’s Systematic Theology:
The Pentateuch connects the name with the Hebrew verb hayah, to be, Ex. 3:13,14. On the strength of that passage we may assume that the name is in all probability derived from an archaic form of that verb, namely, hawah. As far as the form is concerned, it may be regarded as a third person imperfect qal or hiphil. Most likely, however, it is the former. The meaning is explained in Ex. 3:14, which is rendered “I am that I am,” or “I shall be what I shall be.” Thus interpreted, the name points to the unchangeableness of God. Yet it is not so much the unchangeableness of His essential Being that is in view, as the unchangeableness of His relation to His people. The name contains the assurance that God will be for the people of Moses’ day what He was for their fathers, Abraham, Isaac, and Jacob. It stresses the covenant faithfulness of God, is His proper name par excellence, Ex. 15:3; Ps. 83:19; Hos. 12:6; Isa. 42:8, and is therefore used of no one but Israel’s God. The exclusive character of the name appears from the fact that it never occurs in the plural or with a suffix. Abbreviated forms of it, found especially in composite names, are Yah and Yahu.