hey guys I am new to ubuntu I am trying to use the command "apt-get install vim" but it actually not installing I cannot understand what that means so i am copying it down what the terminal is showing. I am sure vim and vi both have been installed but while using vi editor the backspace and the arrow button does not work as the way it is suppose to work. 

```
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package vim is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

```

Thanks