About Us Summary in the Sidebar

I have been searching the forums and google for days trying to find out the answer to this one…

How do I add a summary from a page (in this case the about us page) in the sidebar? I am assuming you can do so with the if(is_page) condition but I am not sure how to write it out

Basically I am looking for this:

Sidebar

ABOUT US
Short summary here
<read more>

—

Any suggestions?