E: Unable to locate package repo
this error comes after
sudo apt-get install repo
means that you tell your system to see if there is a package called
So this is normal!
As Rinzwind explains, there is no package called
In your case that would be
Feel free to ask another question to get help on what you are more specifically installing.
If you're trying to download AOSP sources using the
Google provides instructions to download the tool manually:
You should now be able to run