Open a new Bash console under Start new console / Other.
You can now clone your GitHub project by typing: git clone into the console. If you want to copy and paste the repo URL, here's how to copy/paste into the console. Use the https URL if you haven't set up SSH keys on PythonAnywhere; the process for setting up SSH keys here is just the same as it is on a Linux machine -- see GitHub's help pages for more information.
Once the clone is complete, cd into the newly-cloned directory to have a look at the result. You can use pretty-much all Bash commands and built-ins in the console.