What does this mean? "Most of the money supply is made of of intangible computer entries?"

Money is the medium for exchange of goods or services.
Without money people will have to barter the goods and services they have or produce in
exchange for other goods and services they want. This process of exchange becomes very
easy when people are able to exchange goods and services for money. Thus money acts as
lubricant that facilitates the process of exchange in an
economy.

We generally think of money as coins and paper
currency. But in reality the money that is represented by assets like money in bank
accounts is also are used for payments, and therefore is money. For example, we may make
payment by cheque. This type of money including coins, currency and deposits in bank
checking or current accounts is designated as M1 type of money. There is another broader
concept of money called M2 money. This type of money includes all M1 type of money plus
certain other type of liquid assets such as saving accounts, and money market
funds.

The statement that "most of the money supply is made
of intangible computer entries" is pointing towards the fact that in the total amount of
M2 money supply, the proportion of the physical money in form of coins and currency
notes is very small. Most of M2 money is in form of other liquid assets, and amount of
this kind of money is not represented by any physical asset but by entries in accounts
of various organizations.