This means that they had touched a dead man's body. You can make the full meaning of this statement clear. Alternate translation: "because we have touched the body of a dead man" (See: [[rc://en/ta/man/translate/figs-explicit]])
The men ask this question in order to complain that they are not allowed to participate in celebrating the Passover. This rhetorical question can be translated as a statement. Alternate translation: "It is not fair that you keep us away from offering the sacrifice ... among the people of Israel." (See: [[rc://en/ta/man/translate/figs-rquestion]])