The appendix on the value form might be helpful.

”The analysis of the commodity has shown that it is something twofold, use-value and value. Hence in order for a thing to possess commodity-form, it must possess a twofold form, the form of a use-value and the form of value. The form of use-value is the form of the commodity’s body itself, iron, linen, etc., its tangible, sensible form of existence. This is the natural form (Naturalform) of the commodity. As opposed to this the value-form (Wertform) of the commodity is its social form.”

If commodities have a two-fold form, then there is correspondingly a two-fold form of the labor that produces them.

Just as commodities are viewed abstractly (via real exchange relations) as uniform value, abstracted from use-value, so also is the labor that produces value seen as a homogeneous human labor, abstracted from the particular trade or type of labor. Likewise, the type of labor that produces use-values or particular types of commodities, is itself a concrete labor of a definite kind like cotton spinning, baking, metalworking, etc.

Concrete labor produces concrete use values.

Abstract labor produces value.

The big term that he’s getting at there is ‘social labor’ which is the form of labor that occurs within capitalist production (and socialist production).

Individual labor creates, as quarrk pointed out, use value. Something that is produced to be immediately consumed. Social labor produces exchange value, something that is means not to be immediately used, but to be exchanged for something else.

The thing with exchange value is that under capitalist production, the capitalist controls the exchange and the laborers only receive a portion of the exchange value they produce. So this ‘dual character’ of labor ends up feeding into the primary contradiction of capitalism which is wage labor.