On clicking Site Identity you can see the new tab like the image below.
- Logo( Only available in WordPress version greater than or equal to 4.5 ): It changes the main logo of the site.
- Site Title : It changes the main site title of the site.
- Tagline : It changes the tagline (i.e:Description) of the site.Just below site title.
- Display Site Title and Tagline: This enables/disables the site title and tagline from the site
- Site Icon : The Site Icon is used as a browser and app icon for your site.Icon must be square and at least 512px wide and tall.