This feature lets you share messages to a channel or to a member.
How it works:
Go to the message you want to share and click on 3 dots where you see an option for share.
Search for the person you want to forward the message to, click on the profile, and it's done.
P.S. - You can forward only one message at a time.
Share message serves the purpose of sending a text received from someone to a different concerned person, without actually typing it again and not changing the body of the text either.
It helps to send the received message the way it is received efficiently. It can also be shared to a number of people, thus helping you spread the required message at a faster pace.
Refer this video to see more in details - https://youtu.be/IFvDYUd04DY