Electrical conduction due to mobile carriers in ferroelectric domains and domain walls has been extensively studied in recent years for their potential applications in nano-electronics. On the other hand, the dielectric loss due to dipolar relaxation and domain wall oscillations is of paramount important for ferroelectric devices working at radio and microwave frequencies. Using a combination of conductive atomic force microscopy (C-AFM) and scanning microwave impedance microscopy (MIM), we demonstrate the local conductivity mapping at both dc and GHz frequencies in hexagonal (Sc,Lu)FeO₃ single crystals. Interestingly, while free carriers are responsible for the contrast observed at oppositely polarized domains, the MIM signals at the DWs are clearly dominated by a localized vibrational mode. In particular, the effective GHz conductivity of the DWs, which shows little dependence on the tip bias, is 2 ~ 3 orders of magnitude higher than that at zero-frequency. Our results provide new impetus to incorporate the nanometer-sized ferroelectric DWs into novel high-frequency devices.