What Legacy business is
Slang for a traditional brick-and-mortar firm. Accurate or not, anything characterized as "legacy" is perceived to be old or outdated (as opposed to a new economy company, for example).
The meaning of B2D (Business-to-Distributor)
An acronym that describes online communications and transactions conducted between a business and the members of its distribution channel (such as resellers, distributors, agents, and retailers).