sons. Hebrew text is "son" (singular) But the Hebrew margin, with some codices and one early printed edition, read "sons" (plural), as here: i.e. Seleucus II (Callinicus) and his brother Antiochus III. See Encycl. Brit., 11th (Cambridge) ed., vol. 24, p. 604.
shall = he shall: i.e. Antiochus III, the second king of the north, his brother having died by a fall from his horse.
come. Some codices, with one early printed edition, and Syriac, read "come against him".
be stirred up = will wage war. Defeating Antiochus III.