מלכים ב י״ח:א׳-ח׳

בשנת שלש. למרדו של הושע:

In the third year. Of Hoshei'a's rebellion.¹See above, 17:1, and Rashi there. ²I.e., in the third year of Hoshei'a's rebellion against Ashur and declaring his independence, Chizkiyoh became king.—Metzudas Dovid

ויקרא לו נחשתן. לשון בזיון, כלומר מה צורך בזה, אינו אלא נחש נחושת:

And he called it Nechushton. A derogatory expression,³The additional “nun” to the word נחשת serves to belittle and mock the subject. See II Shmuel 13:20. as though to say, “Why is this necessary?⁴The copper serpent was not destroyed before now because it was incorrectly believed that one may not destroy any object that was made as a result of a Divine command. The serpent was originally made to encourage the Bnei Yisroel to pray to God after they were bitten by poisonous snakes. See Bamidbar 21:4-10 and Tosfos in Maseches Chulin 7a. It is also possible that they kept the copper serpent as a remembrance of the great miracle that occurred, just as they kept the jar of manna, in Shemos 16:33-35. It is nothing but a copper serpent.”⁵Alternatively, the Bnei Yisroel who were worshiping it called it the Nechushton.—Targum

ישכיל. יצליח:

He succeeded. He succeeded.⁶ישכיל stems from שכל [=intelligence]. Adonoy successful person is conceived by others as one who acts with intelligence.—Metzudas Dovid ⁷As in, “Dovid was successful [=משכיל] in all his ways,” in I Shmuel 18:14.