Q:

Detailed infromation about this command

I am newbie in Linux and so need to know a detailed information regarding explanation of this command
sudo bash -c 'for i in update {,dist-}upgrade auto{remove,clean}; do apt-get $i -y; done'

A:

The command can be broken down into the following parts:

sudo: With root privilege
bash -c '...': Execute the command wrapped in single quotes with bash, the standard shell coming along with most linux distros
for i in update {,dist-}upgrade auto{remove,clean}; do ...; done: This is a for loop in bash.  
 The part update {,dist-}upgrade auto{remove,clean} is actually an array with elements being update, upgrade, dist-upgrade, autoremove, autoclean, and the variable i will take each of these values in order.  You'll get more information in advanced bash script guide. 
apt-get $i -y: What is finally executed.  i is the loop variable.  -y means answer yes by default.  You can find more information with the command man apt-get. 

So basically this command is equivalent to the following commands

sudo apt-get update -y
sudo apt-get upgrade -y
sudo apt-get dist-upgrade -y
sudo apt-get autoremove -y
sudo apt-get autoclean -y

That's a complete upgrade and cleanup of the softwares in your system.