To see the new addition, you must be part of the Skype Insider program for beta testers, which you can sign up for on the company's website. To get to screen sharing, beta testers can tap on the ellipsis icon during a call and select "Share Screen." Skype didn't give any indication about a wider launch for the feature.
Earlier this month, Skype increased the number of users that can be on the same audio or video group call to 50 (previously the max was 25). This update put Skype ahead of Apple's FaceTime for the number of users that can take part in a group call, since FaceTime supports a maximum of 32 people.