What does 1 Kings 1:5-14 mean?

Now Adonijah the son of Haggith exalted himself, saying, “I will be king.” And he prepared for himself chariots and horsemen, and fifty men to run before him. His father had never at any time displeased him by asking, “Why have you done thus and so?” He was also a very handsome man, and he was born next after Absalom. He conferred with Joab the son of Zeruiah and with Abiathar the priest. And they followed Adonijah and helped him. But Zadok the priest and Benaiah the son of Jehoiada and Nathan the prophet and Shimei and Rei and David’s mighty men were not with Adonijah. Adonijah sacrificed sheep, oxen, and fattened cattle by the Serpent’s Stone, which is beside En-rogel, and he invited all his brothers, the king’s sons, and all the royal officials of Judah, but he did not invite Nathan the prophet or Benaiah or the mighty men or Solomon his brother. Then Nathan said to Bathsheba the mother of Solomon, “Have you not heard that Adonijah the son of Haggith has become king and David our lord does not know it? Now therefore come, let me give you advice, that you may save your own life and the life of your son Solomon. Go in at once to King David, and say to him, ‘Did you not, my lord the king, swear to your servant, saying, “Solomon your son shall reign after me, and he shall sit on my throne”? Why then is Adonijah king?’ Then while you are still speaking with the king, I also will come in after you and confirm your words.”

English Standard Version (ESV)