The files in /dev define the various devices. The partition sda1 is a block device. It holds data in blocks. The command ls will list the device as such
Originally Posted by davidmenges
Note the b on the far left. This connotes that this is a block device. The user can't see any information like you would see in a directory. See a directory listing here
brw-rw---- 1 root disk 8, 1 Jan 16 10:31 /dev/sda1
Note the d at the far left. This connotes a directory that holds data the can be seen by the user.
drwxr-xr-x 2 bab bab 4096 Jan 15 20:29 Desktop
drwxr-xr-x 5 bab bab 4096 Nov 11 14:20 Documents
In short /dev files are for OS interface with devices, not for the user to use directly.