It's a function that lets you watch live broadcasts.
You can enjoy real-time communication with other pixiv users and exchange comments and❤️, and watch creators draw.
You can watch up to 4 Lives at the same time.
At the moment, Lives can only be watched from pixiv Sketch's web (PC) page.

Live function:

• Watch creators draw in real time
  • Multiple people can enjoy a Live at the same time
• Enjoy real-time communication and exchange comments and ❤️.

* Lives are only available on pixiv Sketch's web (PC) version.
You can start a Live easily from your browser (Chrome, Firefox).