What is the use of following line ..?

Read from bottom to top. I hope you will understand this weirdly written explanation. if not let me know and I will try to put it in another form.

P.S. I broke the line of code and explained each segment.

// 4. create a literal control variable to hold a literal control we find from somewhere else
Literal ltrlCloseWindowText 

// 3. assignment
 =
// 2. type cast the generic control type to literal control
 (Literal) 

// 1. Find a control names ltrlCloseWindowText in the masterpage associated with this page.
this.Page.Master.FindControl("ltrlCloseWindowText"); 

in short, we want to find the value associated with some literal control named ltrlCloseWindowText in masterpage and use it in content page.