Bitcoin is a distributed peer-to-peer digital currency that can be transferred instantly and securely between any two people in the world. 

Bitcoins are the unit of currency of the Bitcoin system, usually shorted as BTC.

A Satoshi is the smallest fraction of a Bitcoin that can currently be sent: 0.00000001 BTC, which is a hundredth of a millionth BTC.

A Bitcoin address is a unique identifier which allows you to receive Bitcoins. The blockchain is a database displayed publicly for every Bitcoin transaction that happened in the Bitcoin network. A block is the ‘current’ part of a blockchain which records some or all of the recent transactions, and once completed goes into the blockchain as permanent database.

To make an analogy with the banking system, the blockchain is like a full history of banking transactions.