Gridlines make it easier to add new content to a design in a way that’s consistent with the overall vision of your microsite. It brings order to a layout that allows visitors to find and navigate through information easily. Grids will also allow you to quickly add elements to a section because many layout decisions are addressed while building the grid structure.
To hide/display gridlines in a grid section:
In the Site Editor, navigate to the grid section where you want to show or hide the gridlines.
In the left panel, open the Styling tab. Under the Layout section, locate Column Count.
Click the eye icon next to Column Count to show or hide the gridlines.