It's kind of like a cheque but works a bit differently: When you print out a pagaré, the bank pays your supplier directly and every month the bank will charge you for everything he paid for you. The document should be generated by Odoo (which is not the case in standard for the moment).

In order to manage them in Odoo, there are few options now:

1 - Install extra modules OCA or from NANOBYTES

2 - Try a workaround to manage them internally. You can generate a Journal just for Pagarés, here is a link to a workaround without installing extra modules. 
NOTE: Print pagarés with this workaround would not be possible.