John Gill Commentary Psalms 77:14

"Thou art the God that doest wonders: Thou hast made known thy strength among the peoples." — Psalms 77:14 (ASV)

You are the God that do wonders
In nature, providence, and grace; it seems chiefly to regard what was done for the Israelites in Egypt, and in the wilderness, see (Psalms 78:12Psalms 78:43) ,

you have declared your strength among the people ;
the nations of the world, who heard what the Lord did for Israel by his mighty power, and with an outstretched arm, as follows.