Taxonomies allow you to change how things are referred to in the system. If you want 'Blogs' to now be called 'News', this is the place to do it.
Head to Settings > Taxonomies and you'll see a list of items that you can change.
When you decide to change the name of an item, be sure to change both the singular and plural version of the label. Take care to make sure it will read properly; for example, the plural of news is news, not newses.
When you're ready, press save. You'll notice the menu items will update.