As the picture above says you need to take action. Until you “sign” the new agreement (by clicking on the checkbox) you will not be able to make any new investments in Prosper even if you have Automated Quick Invest setup.
What this means in reality is that when you invest in notes now you are buying them from Prosper Funding LLC and not from Prosper Marketplace Inc. The original agreement that you approved when you began investing was with Prosper Marketplace Inc. Prosper Funding LLC is what is known as a bankruptcy remote vehicle which provides an added level of protection for investor notes in the event of a Prosper bankruptcy. You can read the details of the new agreement here.