According to an embodiment of the present disclosure, a method for performing sidelink communication by a first device is provided. The method comprises the steps of: transmitting at least one PSSCH to at least one reception device by using at least one sub channel and at least one slot in a resource pool; and receiving at least one HARQ feedback for the at least one PSSCH through at least one PSFCH resource from among M PSFCH resources in the resource pool, wherein the resource pool comprises K PSSCH-associated slots and L sub channels, which are associated with the PSFCH resources, M is greater than or equal to K*L, and K, L, and M may be positive integers.