Freelancers and businesses send invoices to clients to request payment.
With invoices and payments recorded as above, you can track unpaid invoices:
$ hledger bal receivable:supercompany
or list all invoices and payments:
$ hledger areg receivable:supercompany
or just invoices:
$ hledger areg receivable:supercompany amt:'>0'
or just payments:
$ hledger areg receivable:supercompany amt:'<0'
How to translate the data from your ledger into a professional-looking invoice you can send to clients ?
You can create the invoice manually or semi-manually, eg using a tool like Freshbooks, and copy-paste the numbers in.
Or you can automate this somehow. There are few ready-made tools for this, because needs are so diverse.
But you'll find some useful starter scripts in hledger's examples/invoicing directory, such as