The error message means "There is no space to save the file that needs to be saved to be able to install from Extras-devel.". Pretty much exactly what it said.
The strings you see when you run the df command are partitions, size of the partitions, how much is used and how much is left. You will most likely find a string with "root" in it and to the right you'll find "100%" which tells you that the root partition, which is used to save files like the one you need, is full.
There are several pages on the Maemo wiki with suggestions for freeing up space. You could also try to uninstall some programs that you rarely use.
And there you have it: only 4MByte of space left on root file system which isn't enough to save the file you need.
You need to clean up a little. Again, uninstall programs that you are not using any more. If you have installed a lot from Extras-devel, chances are that these programs were not actually finished enough to install their files in /opt which quickly fills the root file system.
The error message means "There is no space to save the file that needs to be saved to be able to install from Extras-devel.". Pretty much exactly what it said.
The strings you see when you run the df command are partitions, size of the partitions, how much is used and how much is left. You will most likely find a string with "root" in it and to the right you'll find "100%" which tells you that the root partition, which is used to save files like the one you need, is full.
There are several pages on the Maemo wiki with suggestions for freeing up space. You could also try to uninstall some programs that you rarely use.
