That's not Acrobat DC.
Tools - Print Production - Edit Object
So people reading this are not too confused, the screen shot is of the old Acrobat Pro X or Acrobat Pro XI, not the current version Acrobat Pro DC.
For lurkers, here's the answer for Acrobat DC.
To get to the Edit Tool, just enter "Edit" in the Search Tools field top right, or click the Edit PDF category name:
And then the Edit tool is the first one in your Tool bar, circled at left in the screen shot below. You use it to edit text or images. The appropriate section of the editing panel on the right "wakes up" when you select text or click on an image or other object. You can also add the Edit button to your Quick Tools set, as I've done upper right (circled), so you just have to click it to start editing any PDF you're looking at.
Hope that helps!