Greetings Augustine3,
Notice what has happend in the Mass beforehand when he says this. The offering has been brought up. The gifts of bread and wine have been brought up to the altar. Our petitions just have been given. The priest is not talking about the Eucharist here, he is talking about the gifts that have been brought up, our “sacrificing” of ourselves too to God, and etc.
That part of the prayer is part of the prayers over the offerings or gifts.
“The Pray, brethern, that our sacrifice may be … and the response made by the people complete the Preparation of teh Gifts and invite the assembly to participate in a living, conscious, and active manner in the major parts fot he Eucharistic paryer that is about to begin.” - pg. 34 Celebrating the Mass by Alfred McBride, O.Praem.
It is not referring to the Eucharist. That is what the Eucharistic Prayer is for.
God Bless.
Anathama Sit