See v. 2; Ps. 46:10. This is the theme of the psalm.
With understanding.
Heb. maśkil, a word of uncertain meaning (see p. 628). Since the term appears in the superscription of a number of the psalms (32, 42, 44, etc.), presumably as a technical designation of such psalms, the clause should probably be translated, “sing a maskil” (see RSV, “sing praises with a psalm”).