A scrolling container is one where the size of the container is independent of it’s content.
For instance you can make a ScrollView or ListView of height 100 pixels, but you can fit as much content in as you want. Similarly regardless of the size of the content in the view, you can set the size the of the View to whatever you’d like.
If a container is scrollable, then Android knows it can shrink the size of the container without rendering parts of the content of the container inaccessible (since the user can just scroll down to see things not on screen). It uses this for when the SoftKeyboard is opened – if a container is scrollable it will shrink it as much as possible in an attempt to keep all of the elements on screen.
So ScrollView, ListView, GridView etc are all examples of scrolling containers.