The claim in the OP makes no sense at all and is typical of Americans talking about German politics: They have no clue at all.
At the times the Nazis became relevant, the two other major parties were the KPD (the K stands for communist) and the SPD (the S is for social democratic). Both parties were clearly to the left of the NSDAP. If the term left wing makes any sense for that time period it clearly applies to those parties and not the NSDAP.
You could also look at who opposed the Nazis and who allied with them. It were the center and right-wing parties who gave Hitler the power to do what he wanted, not the left-wing parties (and that vote only passed when most of the left-wing politicians were in prison and could not oppose it).
You could make the argument that the Nazis were to the left of today's American Republicans, but that says more about Republicans than it says about the Nazis.
At the times the Nazis became relevant, the two other major parties were the KPD (the K stands for communist) and the SPD (the S is for social democratic). Both parties were clearly to the left of the NSDAP. If the term left wing makes any sense for that time period it clearly applies to those parties and not the NSDAP.
You could also look at who opposed the Nazis and who allied with them. It were the center and right-wing parties who gave Hitler the power to do what he wanted, not the left-wing parties (and that vote only passed when most of the left-wing politicians were in prison and could not oppose it).
You could make the argument that the Nazis were to the left of today's American Republicans, but that says more about Republicans than it says about the Nazis.