So they killed the bulls …: It is not clear what the antecedent of the pronoun they is. It appears to be the priests, who were commanded in the previous verse to offer the animals on the altar. But usually the people making the burnt offering were the ones who actually slaughtered the animals (see Lev 1.4-5), in which case the reference would be to King Hezekiah and his officials (verse 20). Or the reference may be to the king and his officials plus the priests. The bulls refers to the seven bulls mentioned in the previous verse.

And the priests received the blood and threw it against the altar: The Law of Moses assigned to the priests the task of throwing the blood of sacrificed animals against the altar (see Lev 1.5, 11; 3.2, 8).

And they killed the rams and their blood was thrown against the altar; and they killed the lambs and their blood was thrown against the altar: The rams and the lambs refer to the seven rams and the seven lambs in the previous verse. The two occurrences of the Hebrew verb rendered was thrown is literally “they threw.” It is an active verb as in the previous sentence with the priests as the subject.

Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Chronicles, Volume 1. (UBS Helps for Translators). Miami: UBS, 2014. For this and other handbooks for translators see here .