Even though the concepts around blockchain technology can be wildly complex, blockchains themselves are quite straightforward. In regular human-speak, a blockchain is just a public database. Blockchains store a history of transactions between parties on a forum that can be accessible by anybody.
Cryptocurrencies are basically digital currencies that can be exchanged online as a form of payment for goods and services. Typically, they're released as part of a new blockchain project and supported by a foundation that may have a role in governing the token direction. Cryptocurrencies are oftentimes managed through governance protocols, where stakeholders vote on proposals for future decisions related to the token. Because tokens and the nodes that manage them are distributed among many parties, a cryptocurrency typically needs buy-in from a majority of token holders to make significant changes.
A smart contract is a self-contained program that defines a public agreement, or "contract" that automatically executes the terms of the agreement when called by a user on the blockchain.
NFTs, otherwise known as non-fungible tokens, are an extension of blockchain technology enabling one-of-a-kind digital collectibles to be generated, traded, and sold on the blockchain. From a technological perspective, NFTs are cryptographic tokens created via smart contracts by adhering to a specific set of standards governing the issuance of the tokens and enabling metadata. This metadata connects the NFT token to its associated content (e.g. an image, URL, or animation).
Every computation or transaction made on the blockchain costs some fees, known in Ethereum as gas. These fees prevent expensive (or endless) contract executions, ensure miners are fairly compensated for the work they do, and provide a fair market to prioritize which transactions make it onto the blockchain.