Proposed is a method for a first device to perform wireless communication. The method may include a step for transmitting sidelink control information (SCI) to a second device through a first physical sidelink control channel (PSCCH) or a first physical sidelink shared channel (PSSCH) related to the first PSCCH, and transmitting data to the second device through the first PSSCH related to the first PSCCH. For example, the SCI may include combination information related to the positions of a plurality of sidelink (SL) resources, and information related to the relative position of a resource on which the first PSSCH is transmitted among the plurality of SL resources.