To edit the text in a Grimlock Navigation block like illustrated below, you’ll need to edit the right menu. Indeed, this block is used to display a WordPress navigation menu.
To edit this menu, you have to select the right menu in Dashboard > Appearance > Menus.
You can change the text displayed by editing the description. If the description area isn’t visible, please take a look at your Screen Options at the top right of your screen and make sure the Description feature is checked.
In the case you want to change the colors or the icons for this menu, please read the following topic: Colours in the “Featured-Homepage” menu?