Pro multis = for many

At least it is faithfully translated:

Eucharistic Prayer II Institution Narrative

Before he was given up to death, a death he freely accepted, he took bread and gave you thanks. He broke the bread, gave it to his disciples, and said: TAKE THIS, ALL OF YOU, AND EAT IT: THIS IS MY BODY WHICH WILL BE GIVEN UP FOR YOU. When supper was ended, he took the cup. Again he gave you thanks and praise, gave the cup to his disciples, and said: TAKE THIS, ALL OF YOU, AND DRINK FROM IT: THIS IS THE CUP OF MY BLOOD, THE BLOOD OF THE NEW AND EVERLASTING COVENANT. IT WILL BE SHED FOR YOU AND FOR ALL SO THAT SINS MAY BE FORGIVEN. DO THIS IN MEMORY OF ME.

Who, as he was handed over and entered willingly into his Passion, took bread and, giving thanks, broke it, and gave it to his disciples, saying: TAKE THIS, ALL OF YOU, AND EAT OF IT: FOR THIS IS MY BODY WHICH WILL BE GIVEN UP FOR YOU. In the same way, when supper was ended, he took the chalice and, once more giving you thanks, he gave it to his disciples, saying: TAKE THIS, ALL OF YOU, AND DRINK FROM IT: FOR THIS IS THE CHALICE OF MY BLOOD, THE BLOOD OF THE NEW AND ETERNAL COVENANT; WHICH WILL BE POURED OUT FOR YOU AND FOR MANY FOR THE FORGIVENESS OF SINS. DO THIS IN MEMORY OF ME.