Alpha, is the first letter of the Greek alphabet; Omega is the last and they are said as their own words, “Alpha” and “Omega” respectively something that the Greek language took from the Hebrew Aleph Bet where each letter has a word and a meaning.
Rev. 1:8 I am Alpha and Omega, the beginning and the ending, saith the Lord, which is, and which was, and which is to come, the Almighty.
9 I John, who also am your brother, and companion in tribulation, and in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos, for the word of God, and for the testimony of Jesus Christ.
10 I was in the Spirit on the Lord’s day, and heard behind me a great voice, as of a trumpet,
11 Saying, I am Alpha and Omega, the first and the last: and, What thou seest, write in a book, and send it unto the seven churches which are in Asia; unto Ephesus, and unto Smyrna, and unto Pergamos, and unto Thyatira, and unto Sardis, and unto Philadelphia, and unto Laodicea.
In the early Christian Church these two letters are frequently combined with the cross or Christ’s monogram (IC) to denote his divinity.
–Easton’s Bible Dictionary
Revelation 22: 12 And, behold, I come quickly; and my reward is with me, to give every man according as his work shall be.
13 I am Alpha and Omega, the beginning and the end, the first and the last.
14Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.
15For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie.
16 I Jesus have sent mine angel to testify unto you these things in the churches. I am the root and the offspring of David, and the bright and morning star.
17And the Spirit and the bride say, Come. And let him that heareth say, Come. And let him that is athirst come. And whosoever will, let him take the water of life freely.18For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book:19And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book.20 He which testifieth these things saith, Surely I come quickly. Amen. Even so, come, Lord Jesus.21 The grace of our Lord Jesus Christ be with you all. Amen.