I can't install updates

mario@mario-HP-260-G2-DM:~$ sudo apt-get update 
Hit:1 http://cran.rstudio.com/bin/linux/ubuntu xenial/ InRelease
Hit:2 http://archive.canonical.com/ubuntu xenial InRelease                        
Get:3 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Hit:4 http://ppa.launchpad.net/appgrid/stable/ubuntu xenial InRelease                               
Hit:5 http://it.archive.ubuntu.com/ubuntu xenial InRelease                                                
Get:6 http://it.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]                               
Hit:7 http://repository.spotify.com stable InRelease                                                                
Get:8 http://it.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]                                       
Fetched 306 kB in 5s (55,1 kB/s)                             
Reading package lists... Done
W: Target Packages (partner/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Packages (partner/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Packages (partner/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Translations (partner/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Translations (partner/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Packages (partner/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Packages (partner/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Packages (partner/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Translations (partner/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4
W: Target Translations (partner/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:45 and /etc/apt/sources.list.d/xenial-partner.list:4

I wonder if this has something to do with my other issues…

  1. Low disk space - What should I do?

  2. Unmet dependencies - How can I fix this?

Thank you in advance for the help!