The means of production and labor with the means of production being the physical non-human inputs that help create the goods and services. This will be factories, machinery, tools, land and raw materials. For example, today we have modern clothing factories with means of production that have sewing machines and fabrics within the building. Labor is the physical human components with mental effort as well that are used during this process of production. This active force is how raw materials are transformed into finished goods. An example could be the garment worker operating a sewing machine to put together a jean jacket.
For the concept of value and basing it on Marxist political theory, value is determined by the amount of socially necessary labor time that is required for the production not on how much an item is liked. Human labor is what gives objects their value. Without that labor what value is there? The raw materials will gain their economic value when the human effort is applied for the transformation which in turn is used for commodities.
The relationship between labor and value is that they are both intertwined because labor is the source of all economic value. If there is no human labor, the machines and raw materials stay untouched with nothing new being produced. The transformative force of labor transfers the existing value of the materials and tools making it a new commodity while generating brand-new value for the production process.
Labor vs Labor Power are vastly different. Labor power is the worker having the capacity to work which includes their brain power, skills , knowledge , and muscles. Under capitalism, this type of commodity is how workers sell what they bring to their employer which in turn earns them a wage.
Labor is the exercise of this capacity which is the work actually being done on the clock. The capitalist exploitation heavily relies on this difference. The capitalist purchases the labor power for its market value (wages) but it is gained at a higher amount of the actual labor from the worker on their shift.
Surplus value is extra value generated by the workers above and beyond what they are compensated for survival and the return of work. The importance of social class is vital because it shows the underlying mechanism for these class conflicts. Capitalist profit comes from the unpaid labor of workers while the capitalist class owns the means of production. For example, lets say a worker is paid $100 for an eight hour shift. Within those first two hours the worker already produced $100 worth of products which in turn they paid for their daily wages. Those leftover six hours , the worker will continue to produce goods and services worth another $300. The extra amount is the surplus value that goes to the owner.