It depends on how you want to manage the items in grid. If you are OK with writing some CSS and using Magento's WYSIWYG editor's capabilities (adding HTML table), this is easy - update Home Page content and done. If, however, you want this grid to be responsive (you should have it responsive, just like your whole site should be), this might require A) more advanced input from you - writing specific HTML that displays images neatly + having custom CSS developed prior to that, B) have custom extension developed to allow only image + link data to be entered (or whatever data you need) - you get nice & easy usability, lose risk of messing the content up... spend more money/time on development.
All in all, task is really easy.