This latin phrase can be translated into English to "who takes away the sins of the world". It is found in various versions of the
Mass and
Requiem in reference to
God the son as an opening to various requests, such as...
Pie Jesu Qui tollis peccata mundi. Dona eis requiem. Agnus Dei Dona eis requiem sempiternam. (Merciful Jesus, who takes away the sins of the world. Grant them rest, Lamb of God. Grant them everlasting rest.)
Naturally, it's found in the slew of compositions based around the words of the
Mass. While learning
Mozart's "Great Mass in C Minor",
our conductor instructed us to pronounce the phrase as would
The Count from
Sesame Street.
If I may improvise <coughs>:
Qvi tohlihs peycaaarta mMHUUUUUUUNNnnnndiii (Ah-Ah-Ah)