This move behind it is to make people, especially users, increasingly aware of and use sign language by introducing a new Lens that recognizes American Sign Language (ASL) and translates the gestures into the app. According to Snap :

"We're always looking for ways to help Snapchatters expand their expression and connect even more with the Camera. Today, we're launching a new Lens, in partnership with SignAll, which is the first ASL Alphabet Lens. It encourages Snapchatters to start learning American Sign Language!

Looking at the sequence above, the new Lens teaches its users how to fingerspell by different games and exercises developed within the app.

The new Lens was constructed with Snap's developing hand-tracking technology, which allows for more communicative capacity, in new forms, through the application. Snapchat used the same technology to power a series of similar Lenses launched last year, part of International Week of the Deaf that also encouraged users to fingerspell various words.
The new Lens takes it a step forward and provides more in-depth interpretation and demonstrations to enlighten even more people about the correct utilization of ASL hand gestures.

This can indeed be an effective awareness-raising measure which would assist in increased inclusion - that is not only being done, but Snap is also exploring other applications of its hand gesture recognition technology, which may enable greater means of communication to the deaf and hard-of-hearing audience.

"For native signers, in a world where linguistic inequity is prevalent, we believe AR can help evolve the way we communicate. We look forward to learning more from our community as we strive to continually improve experiences for everyone on Snapchat. "

It's a good experiment, and a great way to get more people more aware of sign language, and maybe at least learn the basics via these examples and games.