Libffi is a system library needed by python cryptrography library.
https://cryptography.io/en/latest/installation/
The error is fairly self evident
No package 'libffi' found
Package libffi was not found in the pkg-config search path.
Below is someone else who had a similar issue issue.
Also note: the category you were after is help. As you are not able to configure or install a couple of other bits of information would have been useful such as the installation method you are using to install certbot. The server section is more about configuring servers with TLS once a cert is obtained.
Also- take appropriate steps before installing or upgrading things as they may break other things.
Andrei