In the app if you go to the payments tab then request money, click "by QR code or link", it'll give you a QR code to scan and an option to create a link. I generally use it to request money from my bandmates if I've booked the rehearsal studio as you can set the amount and a custom description for the transaction to appear on their bank statement, e.g. if you sold an Ampeg amp, you could call the description "[your name] Ampeg amp purchase via BC" or something similar that fits within any space constraints.