Literally 'sounds dāng-dāng' — the onomatopoeia 当当 (dāngdāng) is the clang of a bell or struck metal, so 响当当 is something so solid that hitting it produces a clear ringing sound. From there: 'a name that rings out'.
usage
Almost always attributive (响当当的人物 / 响当当的品牌 / 响当当的招牌). Carries a positive, slightly admiring tone.
