1
I don’t have many money left.
I don’t have much money left.
Money is an uncountable noun, so use much, not many: ‘How much money do we need?’ In positive sentences, a lot of is common: ‘She has a lot of money.’
2
My friend lent me a money for the bus.
My friend lent me some money for the bus.
Do not put a before money. Use some money when you do not say the exact amount. If you mean one piece of money, use a countable word such as coin or note: ‘I found a coin at the bus stop.’
See LEND