How many cakes do you think I have in front of me?
I have three cakes on the table in front of me (countable - you are able to count the cakes: 1, 2 and 3): One is an apple cake; another is a custard cake; and the other is a chocolate cake (I am getting hungry now!!!).
Which one do you like? The chocolate cake? Okay, how much chocolate cake do you want (you are not able to count the amount of cake, you measure the amount of cake that you want)? Half!
A business can be countable.
She has many businesses: some are high tech computer businesses, others are manufacturing businesses (you are able to count the number of businesses that she has).
For uncountable, consider this:
There is not much business going on in the fishing industry in our country. This is again a measure of how "busy" the fishing industry is.
Countable/uncountable noun: Can you count the noun?
I am sure there are others who help you in a much more coherent fashion. Good luck!