I need help understanding how the POS works, especially in Offline Mode. Also, what does the following(Draft, Unpaid, ) invoice status mean Unpaid Invoice Status mean
In the Offline mode, you can use POS without internet connection as well. It syncs all the masters, so that you can create invoices. When net is available, all the offline invices are sycned.
Unpaid invoices are one against which payment is not received.
Draft means the transaction is yet to be submitted. This usually happens in offline PoS when a condition makes ERPNext to reject the transaction. Example is if you have insufficient quantity and negative stock is not allowed.
Unpaid means the transaction is submitted and completed but payment is yet to be taken or payment is incomplete.
Regards