WhatsApp is rolling out message reactions to a section of Beta testers on the latest update 22.214.171.124. for users. The six available reactions are: Like, Love, Laugh, Surprised, Sad, and Thanks.
According to official WhatsApp tracker WABetaInfo, the feature was already in the pipeline as the messaging app already rolled out the ability to manage reaction notifications on WhatsApp beta for iOS and WhatsApp Desktop beta.
Only a few beta testers will be able to react to messages in this small test, but everyone can now see message reactions (If the tester is in their networks). The rest of the WhatsApp users will have to wait for the company to officially roll out the feature publicly, although it is still not clear when this will be done.