Learn English – “We have lot of money” or “We have a lot of money”

In ordinary usage, nouns like "milk" and "water" are uncountable.  There are times, however, when such words do have a countable sense.  For example, cows produce a different milk than goats.  If I want to compare those two milks, then I'm using the word "milk" in a countable sense and phrases like "a different milk" and "those two milks" are natural and sensible. 

In financial contexts, it is natural and sensible to talk about different countable monies.  The USD and the Euro are two different monies.  Taxable income and tax-free income are two different monies. 

Strictly speaking, it isn't necessary to force a countable sense onto an uncountable noun.  It is just as natural and sensible to talk about "two types of milk" or "two kinds of money", which allows "milk" and "money" to retain their ordinary, uncountable meanings.  Your cited definition includes the phrase "as used in financial contexts".  A better phrasing might be "as used in financial jargon".