If you activate this option, it means, that the process will proceed with the next step only after all members of the role, assigned to the form, have filled in the form. This makes sense when you need for example the approval of all members of a role. However, you can also add a period of time (Working days or Working hours), in which the members of the role have to fill in the form. After this period of time, the process will proceed, even when not all members have filled in the form.
What is a form fulfilled by all members?