Automatically mutes and hides the Twitch player when an advertisement started and revert it back to normal once finished. The stream can still be heard during ads. You can also display ads via the "Ads Options" button.
< Feedback on Twitch - Mute and hide ads, while keeping the audio of the stream on
If by that you're asking if you can do something else during an ad, like checking another tab, you sure can. I often have one or two streams on the side, and it's working perfectly.
Is it possible to switch tab if an ad starts playing?