The arrow in his hand is the "Symbol of fate". The captives, wearing long garments, and bare-headed, showing curly hair, were brought before him. The luckier ones were decapitated (Sennacherib pointed his arrow up). The less lucky ones were pegged to the ground, skinned alive, and left suffer an excruciating death (Sennacherib pointed his arrow down). These were probably Hezekiah's men, who encouraged the city to resist. These are the probably the earliest picture we have of men from Judah.
Other prisoners are spared, and are carrying out their possessions on bullock carts or a camel. These are dressed differently, wearing a kilt and a headdress of a scarf with one end hanging down besides their ears. These people were deported and were used as labour to build Sennacherib's palace (where these reliefs came from). More reliable people were enlisted into the Assyrian army.
After Lachish, Jerusalem was next, but Isaiah prophesies:
Therefore thus says the Lord concerning the king of Assyria: He shall not come into this city, or shoot an arrow there, or come before it with a shield, or cast up a siege mound against it. By the way that he came, by the same he shall return, and he shall not come into this city, says the Lord. For I will defend this city to save it, for my own sake and for the sake of my servant David. (Is 37:21-29, 33-35)
That night the angel of the Lord passed through the Assyrian camp, and 185,000 died in one night
Then the angel of the LORD set out and struck down 185,000 in the camp of the Assyrians; when morning dawned, they were all dead bodies. (Is 37:36)
As Isaiah prophesied, Sennacherib did not enter the city or shoot an arrow there. He withdrew to his land, and one day, twenty years later (681 BC), while worshipping in the temple of Ishtar, his sons slew him.
Then King Sennacherib of Assyria left, went home, and lived at Nineveh (and built his palace with these reliefs). As he was worshipping in the house of his god Nisroch, his sons Adrammelech and Sharezer killed him with the sword, and they escaped into the land of Ararat. His son Esar-haddon succeeded him. (Is 37:37-38)
When the king died, all of the likely contenders would be put to the sword, all his wives and children were slaughtered except the favourite son and his immediate family. Sennacherib was hated by his sons, and while he was worshipping, they suddenly killed their father with the sword. Certain guards, already primed, guarded these sons who then hacked him to pieces. Racing from there all throughout the place was a great killing and murder. An axe blow obliterated his face, almost certainly on the very night of the assassination - a vivid testimony to Isaiah's predictions.