"Set conflict" in assigning reviews, what does that mean?

When I assign reviews, which effect has the option "set conflict"?
How do I use it?

When you assign reviews, you can always identify a "Conflict of Interest" or COI. PC members or reviewers might have competing interests that could unduly influence their responsibilities in the review process and therefore should not be allowed to review submissions or access review details.

Competing interests may include, but are not limited to, financial ties, academic commitments, personal relationships, political or religious beliefs and/or institutional affiliations.

If you set a conflict, the PC member or reviewer will not be considered during the process of automatic review assignment and she/he will also not be able to access the corresponding submission in the "PC Online Forum" of ConfTool Pro.

ConfTool Pro will determine institutional affiliations and set conflicts of interests automatically.
You can find more information here: How does ConfTool Pro identify Conflicts of Interest (COIs)?