This verse from 2 Kings 17:2 refers to King Hoshea of Israel, the last king of the Northern Kingdom before it fell to the Assyrians. Let's break it down:

"He did that which was evil in Yahweh’s sight": This is a common refrain in the Books of Kings, indicating that Hoshea was not a righteous king according to the standards of the Deuteronomic historian. It implies that he engaged in practices that were disobedient to God's laws and commandments, likely including idolatry and other forms of religious corruption.

"Yet not as the kings of Israel who were before him": This is the crucial part. It suggests that while Hoshea was evil, he was less evil than his predecessors. This could mean:

Less severe idolatry: He might not have embraced idolatry as fervently as some previous kings. Perhaps he paid lip service to Yahweh while also tolerating other gods, a less extreme form of apostasy.
Less oppressive rule: His policies might have been less cruel or unjust compared to other kings. He may not have been as ruthless in extracting tribute from his people or engaging in internal conflicts.
A degree of compromise or reform: It's possible Hoshea made some attempt, however minimal, to appease Yahweh or to address some of the worst aspects of the kingdom's religious decline. This could have been motivated by political expediency or perhaps a genuine, though limited, desire for reform.

In essence, the verse presents a nuanced picture of Hoshea. He was still considered a wicked king in the eyes of the biblical author, but his reign was not as depraved as those of some of his predecessors. This might be included to provide some context or perhaps even a slight mitigating factor for the impending doom that was about to befall the Northern Kingdom. The rest of the chapter makes it clear that the kingdom's sins were cumulative and that Hoshea's less extreme wickedness was not enough to avert God's judgment.