The homepage meta title is the name for your store to be displayed in the browser title toolbar. This is important for SEO, and social sharing. The homepage title tag of your store should be a a few words about what you sell. e.g. Jodie's Online Jewellery Store.
To add a meta title to your store go to Configuration > Store Settings> General Settings. You will now see a screen called "Edit Settings". Edit the field called "Meta Title".