UI Components / Transfer list
In your Backendless App, go to the Marketplace -> User Interface tab and install the Transfer list componentInstall the component to the UI Container of your choice

UI Components Guide - Transfer List

Transfer list is a component for Backendless UI Builder designer.
It allows you to move one or more list items between lists.

Customizations include multi-select options and source of list items (JSON or Codeless).

UI Components / Transfer list