There's no need for interpretation, Smith makes it quite clear with nearly an entire chapter dedicated to it:
> The value of any commodity, therefore, to the person who possesses it, and who means not to use or consume it himself, but to exchange it for other commodities, is equal to the quantity of labour which it enables him to purchase or command. Labour therefore, is the real measure of the exchangeable value of all commodities.
> It was not by gold or by silver, but by labour, that all the wealth of the world was originally purchased; and its value, to those who possess it, and who want to exchange it for some new productions, is precisely equal to the quantity of labour which it can enable them to purchase or command.
> But though labour be the real measure of the exchangeable value of all commodities, it is not that by which their value is commonly estimated.
https://www.gutenberg.org/cache/epub/3300/pg3300-images.html...