The Book of Hebrews is a letter written to encourage discouraged Christians. The particular Christians first addressed in the letter came from a Jewish background and faced some forms of persecution from their Jewish friends and relatives. We may not share their exact circumstances, but the principles of encouragement God spoke to them continue to speak to us today, as we see Jesus to be better than any of the things that discourage us.
We don’t know who the human author of the Book of Hebrews, but no matter who the human author is, there are indications that it was written fairly early in the New Testament period, probably somewhere around ad 67 to 69. The reference to Timothy (Hebrews 13:23) places it fairly early. It also makes no mention of the destruction of the temple, which means it was probably written before the temple was destroyed in ad 70.