How do I give my staff access without showing them everything?

Yes. Under Settings → Roles & Permissions:

1. Open Manage Roles, add a role, then click Permissions on its row and tick only what that team needs. A new role starts with no access.
2. In Manage Staffs, click Invite staff, enter their email and pick the role. They set their own password from the emailed link.

A staff member can only view or change what their role allows. Create a narrow role for the packing team (for example orders only) and keep settings, payments and reports for owners. The number of staff accounts depends on your plan; the Free plan has none.