You can create a dividing line across a page of your Word document with just a few keystrokes:

• Type three consecutive hyphens --- and press the Enter key to get a normal line.
• Type three underscores ___ and press the Enter key, and you'll get a bold line.
• And if you type three equal signs === and press the Enter key, you'll get a double line.

image credits:
• photo of a hand drawing a line by Michael Lorenzo (aka nazreth) via FreeImages
• screenshot of line examples by me