class selector in css -

I am working with Bootstrap and I am confused with CSS. They have a class selector in their CSS code. I do not understand what this code actually does. Does this CSS only apply to Span or others?

  .row-fluid [class * = "span"] {display: block; Swim left; Width: 100%; Minimum height: 28px; Margin-left: 2.127659574%; * Left margin: 2.0744680846382977%; -WebKit-box-size: border-box; -MOZ Box-Size: border-box; -mm-box-size: border-box; Box-size: border-box; }    
 
 
 This is a partial characteristic, and anything applies to the string  Duration  is the class name in it, it is used for  span2  and so on. For example  [class * = "span"]  will match these elements:  
  & lt; P class = "span" & gt; & Lt; / P & gt; & Lt; P class = "spanner" & gt; & Lt; / P & gt; & Lt; P class = "espanol" & gt; & Lt; / P & gt; & Lt; P square = "span 43 blue" & gt; & Lt; / P & gt;