Bill.com is an online service for companies to send invoices to their customers and pay bills received from their vendors. Normally, when a vendor or contractor does work for a company, they send the company an invoice or bill for the work they performed. Part of the benefit of doing contract work through Facet, is the streamlined and hassle free billing and payments process.
At the end of every pay period, we take the hours you've submitted in Harvest, generate an invoice for your work, and send it to the client. We also generate a bill in Bill.com that records what Facet owes you for that pay period.
If you log in to your Bill.com, you will see the bills the Facet team as entered on your behalf. Because Facet entered the bill for you and you didn't create the bill and send it to Facet, the bill will be marked as "Unsent". In other words, the bill is "unsent" because you didn't have to create an invoice and send it to Facet to get paid for your work. You can safely ignore the "unsent" label.
This is just one of the quirks of using a platform that isn't perfectly tailored to the way Facet works.