ABS = Asset-Backed Securities

ABS are securities derived from a pool of underlying assets. To create asset-backed securities, financial institutions pool multiple loans into a single security that is then sold to investors.

The pools can include many types of loans (mortgages, credit card debt, student, auto, …).
As many of the loans cannot be sold separately, securitizing them into asset-backed securities provides investors with further investment opportunities, and allows financial institutions to remove risky assets from their balance sheets.