This application relates to the field of wireless communications technologies, and provides a method for communication between terminals, a network-side device, and a terminal. The method discloses that the network-side device allocates, to the terminal, time-frequency resources for transmitting uplink information and sidelink information. On the time-frequency resources and at a same moment in a range of time domain-frequency resources, the terminal transmits the uplink information used for performing uplink beamform training to the network-side device, and transmits the sidelink information used for performing sidelink beamform training to another terminal. According to solutions provided in this application, based on conventional uplink and downlink beamform training procedures, the terminal performs the sidelink beamform training without additionally using a new time-frequency resource.