What they are showing you is the autocomplete option. If you type 'una' and then press enter, it will finish the command for you by displaying 'uname'. This is extremely helpful when changing directories. Let's say you are going into your home directory from '/'.

dsanta# cd /ho<tab>
dsanta# cd /home

By pressing the tab button it finishes the word 'home' for you.

dsanta#cd /home/d<tab>
dsanta#cd /home/dsanta

Just makes it eaiser than to type out the whole thing. Sometimes you will have more than one choice to finish the word. Since 'autolist' is set by default in RedHat, you can press tab twice to get a list of possibilities. For instance:

dsanta# cd /usr/l<tab>

As you see, the <tab> didn't finish anything. Press <tab> again and it will show like this:

Code:
dsanta# cd /usr/l
lib       libexec      local
dsanta# cd /usr/l
If you put an 'o' after the "cd /usr/l" and press <tab> it will compete it as "/usr/local". If you type 'i' after "cd /usr/l" it won't finish since there are still 2 possibilities. Hope that helps.