A method for a first device to perform wireless communication and a device supporting same. The method may include the steps of: receiving, from a base station, a time division duplex uplink-downlink (TDD UL-DL) configuration including information related to a UL resource; receiving, from the base station, information related to the start of sidelink (SL) symbols, information related to the number of the SL symbols, and a bitmap indicating one or more slots included in an SL resource pool; and determining the SL resource pool.