In his days Sennacherib came up, and sent the Rabshakeh: See 2 Kgs 18.13, 17. In his days refers to Hezekiah’s reign as king, so this phrase may be rendered “While Hezekiah was king.” Sennacherib was the king of Assyria. Came up means that Sennacherib invaded Judah; Good News Translation “attacked the city” is wrong. Rabshakeh was the title of a high Assyrian official. Good News Translation translates it as “chief official” while Contemporary English Version has “highest officer.” The Revised Standard Version footnote at the end of the second line indicates that some manuscripts add “and departed.” Others add “from Lachish,” which Good News Translation has translated. See 2 Kgs 18.17. The model below will omit both.

He lifted up his hand against Zion and made great boasts in his arrogance: See 2 Kgs 18.19-25, 28-35. He lifted up his hand against Zion means that the Assyrian official threatened and attacked Jerusalem. Good News Translation translates “He challenged Jerusalem.” Zion here is Jerusalem and in many languages will be rendered “the people of Jerusalem” (see the following verse). Made great boasts in his arrogance means that the Assyrian official was arrogant, so he boasted. Good News Translation has “boasted arrogantly,” but Contemporary English Version translates “This arrogant officer boasted.”

An alternative model for this verse is:

• While Hezekiah was king, King Sennacherib of Assyria attacked [or, invaded] Judah. He sent his chief official to Jerusalem, * and this man boasted arrogantly, daring the people of Israel to defy Assyria.
* Some manuscripts add and departed; others add from Lachish.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.