Economics Value vs Volume

Value is linked to the benefit derived from consuming a good or service. I may pay £1 for a chocolate bar, but if I didn't value the bar as greater or equal to £1 there would be no point in me buying it.
Volume is just simply the quantity.

Thanks for your response. So for firms the volume is the number of products sold. What is value for firms? Sorry I’m just trying to get my head around it.

A firm's value can mean the cumulative worth of its assets.
Though in terms of chocolate bars, the profit I attain from producing chocolate bars has a higher value than the work I put in to make it, otherwise I wouldn't produce it.
Don't get yourself too tied up in these terms, it's not worth it.