If you use both Excel and Word you may well want to copy data from Excel into Word and what would be really convenient is if the data in Word updated when you change it in Excel. Well that is what you can do and it is really quick and easy to do.
You do not have to link it and there is an option to just copy and paste the data in, but there are times when you want to reuse the document with updated data as it comes in or you may still be entering data or reviewing calculations but want to get on with inserting it into Word so that others can review it or to get a feel for the layout.
Data from Excel can also have data feeding in to it so you may want that reflected in your Word document.
What you want to do is link the data into Word using Paste Special.
Here is a video tutorial on how to do this.