i want to use ppsspp emulator on ubuntu. but i couldnt install due to some errors

Here you have two problems with repositories - they do not have packages for Ubuntu 20.04 LTS.

So you need to remove these repositories at first with

sudo add-apt-repository -r ppa:danielrichter2007/grub-customizer
sudo add-apt-repository -r ppa:ppsspp/stable

and then add repository which provides ppsspp package:

sudo add-apt-repository ppa:samoilov-lex/retrogames
sudo apt-get update
sudo apt-get install ppsspp