How can I see which settings have been made in an pdf?

Open the pdf in Acrobat and go through View>Tools>Print Production>Set Page Boxes. Use the "Apply to:" drop-down menu to choose how you want the dimensions to display. You will have to have defined the bleed amount in the original application from which the pdf has been made (Illustrator, InDesign, etc.) in order for the bleed amount to be accurate.

Note: the 8.5 x 11 bleed size shown in the screen shot is indicating that the document bleed was set to zero in the original 8.5 x 11 document.