Roles manage system users permissions. You can enter individual permissions for each user, but if you want to create identical permissions for a group of users, better use Roles.
- Click Setup > Roles. Choose New role.
- Enter Role name, Parent role if necessary and mark permissions.
- View - entries of all users will be visible;
- View by role - only entries of users who belong to same role or roles below will be visible;
- View (own) - only user's own entries will be visible;
- Go to Staff, select user profile and choose Permissions. Identify Role and press Save.