Dotombori is a riverside neighborhood along the Dotonbori Canal (道頓堀川, Dōtonbori-gawa) that runs from Ebisu-bashi Bridge in the west to Nipponbashi Bridge in the east. It primarily consists of the shotengai (商店街, Shōtengai, Shopping Street) area to the south of the canal, as well as the Tonbori Riverwalk along the canal.
You can find plenty of food stalls along the shotengai, including shops selling takoyaki (たこ焼き, Octopus balls) and kushikatsu (串カツ). The neighborhood has a lively buzz at night, with many izakayas (居酒屋, Japanese pub) in the area.
This is also the area where you'll find Osaka's famous Glico Man sign next to Ebisu-bashi Bridge, as well as the giant crab sign above Kani Doraku.