Communication methods and devices for a sidelink (SL) are provided. A communication method for an SL includes the following. A first terminal device obtains a first transmission resource. The first terminal device sends first feedback information to a second terminal device, by using the first transmission resource. A time unit in which the first transmission resource is located is not used for transmitting data by the first terminal device to at least one third terminal device or the second terminal device, where the first terminal device, the second terminal device, and the at least one third terminal device belong to a first group.