This is Giant Superman 2, published by Mimosa (SA Magazine Co) +/- 1963-1964.
It reprints the cover and this story from DC Comics' Action Comics 273 (1961):
"The World of Mr Mxyzptlk!"
Also reprinted are these two stories from DC Comics' Superman 114 (1957):
"Superman's Billion-Dollar Debt"
"The Man who discovered Superman's Identity"
Also reprinted are these two stories from DC Comics' Superman 121 (1958):
"The Bride of Futureman"
"The Great Superman Swindle"
48pages, glossy colour cover, black and white newsprint interior.
Here is the cover of issue 2 and DC Comics' original cover: