This refers to the eighteenth year of Jeroboam's reign. AT: "After Jeroboam had been the king of Israel for almost eighteen years" (See: [[rc://en/ta/man/translate/figs-explicit]])
Walking represents living, and walking in sins represents committing those sins. AT: "Abijah continued to practice all the sins" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Since these verses refer to several kings, it may help to include the name of Abijah's father. This information can be made clear. AT "that his father, Rehoboam, had committed before Abijah's time" (See: [[rc://en/ta/man/translate/figs-explicit]])
# his time
This phrase represents the time that he was king. The meaning of this can be made clear. AT: "before Abijah was king" (See: [[rc://en/ta/man/translate/figs-explicit]])
# his heart was not devoted ... as the heart of David