If you are new to After Effects become familiar with the User Guide. You're going to waste a bunch of time if you don't. I don't know anyone that has been able to get a hang of AE without some serious study.
Try just to the right of the Magnification Ratio selector. If you hover over the icons in the timeline or the comp panel and have not customized your preferences, you will get pop-up hints that tell you what you are looking at. The icon you want to click on even looks like the Title/Action Safe guide you don't want to see.
Check the user guide. That is just one of many options available in the Composition Panels Grid and Guide Controls drop-down menu. It is in the bottom right. They are just guides, they do not render.