In Exodus 3:13-15, the God of Abraham, Isaac, and Jacob who was known to them as God Almighty, nicknamed Lord by Abraham revealed Himself to Moses as I AM THAT I AM, I AM, YHWH. He told Moses that YHWH was His only name forever
Exodus 3:13-15 ASV
(13) And Moses said unto God, Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? What shall I say unto them?
(14) And God said unto Moses, I AM THAT I AM: and he said, Thus shalt thou say unto the children of Israel, I AM hath sent me unto you.
(15) And God said moreover unto Moses, Thus shalt thou say unto the children of Israel, Jehovah, the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath sent me unto you: this is my name for ever, and this is my memorial unto all generations.
WHAT DOES YHWH STAND FOR?
Good question!
For now, if the translated, 'I AM THAT I AM' and 'I AM' can be also a future tense, we can understand that YHWH implies that, '1 WILL BECOME (be) WHO I WILL BECOME (be)' or 'I WILL BECOME' teaches the incarnation of YHWH when the time was fulfilled (Micah 5:2, Matthew 2:1-6).
Study the necessity which Yehoshua imposes on the remnant Jews (or anyone else) to believe that He is the 'I AM' to not die in sins, in John 8:24. The Jewish Apostle Paul also reaffirms that necessity in Romans 10:9-11.
Who could have been the Messiah (Ruler) who was to be a man in Bethlehem Ephrathah even though He is from old, from everlasting? Think about Micah 5:2. It teaches that the Ruler or Messiah is not an ordinary man but someone from eternity.
Micah 5:2 ASV
(2) But thou, Beth-lehem Ephrathah, which art little to be among the thousands of Judah, out of thee shall one come forth unto me that is to be ruler in Israel; whose goings forth are from of old, from everlasting.