Often it can be really useful to see the name of module position areas on the front end of your website to determine what module you want to edit or to place a new modules into an area you've not used before. You can switch on a toggle that allows you to see the module positions in Joomla, including the name of each module position, in the templates area. To check the "Preview Module Positions" option is switch on, navigate to Extensions > Templates and on the templates screen then click the Options button located near the top right hand corner of your screen.
In the template options screen then you can see the toggle button for Preview Module Positions. Switch this to on. Now on the front end you can add the URL parameter ?tp=1 to your URL to see an outline of each module position and its name. You may need to clear your caching, and remember to switch this feature back off once you've completed your changes.