In plain words
The poet, of Kaṇṭam: The king of Dvārakā, strong-walled and ringed by a sea whose waves beat on it, sided with his brothers-in-law [the Pāṇḍavas], brought the kings [Duryodhana and the rest] to ruin and gave them the kingdom: the seat of Hari [who removes sins], Puruṣōttama, is the eminent city called Kaṇṭam, on the Gaṅgā, where tall sacrificial posts run on in rows without a break and both its banks alike are fragrant with the smoke of sacrifices.