A very common error while installing an application or updating a package is following:
The reason is quite obvious from the error itself “another process using it”. Which means another process is already using the mentioned directory (necessary for the application to be installed) through Synaptic Package Manager, Update Manger, terminal or Ubuntu Software Center.
The idea would be to look for another application which is being installed or update it. Wait for it to finish the installation or cancel it. If you cannot see the application then try running this command in the terminal to solve this error:
sudo rm /var/lib/apt/lists/lock