You can copy information from other sources, like another web page external to your site.
Copying images from another web site is different than copying text. The code that allows the image to be inserted into the web page contains the location that the image is stored. When you copy the image you are also copying the location of the image. If you copy and paste an image into your web site it will slow down the loading of your page as it goes to the other site to retrieve the image. Additionally, if the image is ever removed from the original site, the image link on your web site will be broken.
Copying text that has been created and formatted in a word processor can be time saving, if it is done correctly. Wordprocessors have their own codes built into their text. You don't see them, but they are there. If you copy and paste a word document into a WebPublish page the text and much of the formatting will be captured. Unfortunately a lot of extra code will also be captured. Time saved by copying and pasting can be wasted trying to remove the codes. The best way to paste the contents of a word document into your web page is as Plain Text. This will capture the text but remove the formatting, replacing it with just basic formatting of heading and paragraphs.
Note: When you Paste as a Word Document you may get extra HTML tags or tags that you would not normally use to get the results you want. It is better to paste as a Text file.