I AM Trying to know which module are linked to each other I mean which module do not work without another one like payroll need accounting module and hr .
Here is complete user manual. this may help.
Flow Chart > https://docs.erpnext.com/docs/v13/user/manual/en/introduction/key-workflows
Please use ERPNext instead of next.
@yara I think that this visualization might be helpful: https://frappe.io/blog/development/relationships-between-doctypes-in-erpnext