Crypto is a decentralized trustless ledger.

The 'decentralized ledger' part means it's an automated way to keep track of things (like ownership), secured by cryptography.

Think of it as a way to digitize and transact value, like the internet digitized and transacted information.

The 'trustless' part means that anyone who transacts with the ledger can trust that it's accurate, even though no one is tasked with verifying or updating it.

The implication being that you don't need third parties anymore. This is where a lot of the high value of coins comes from - these coins (representing platforms, businesses, protocols, exchanges, etc) are replacing third parties (like banks, lawyers, notaries . . . governments). What is the sum value of all these third parties in every concivable industry? Higher than the current crypto market cap by a lot, which is why it's safe to say that we're still early. Of course, with the gains of being early comes the risks; who's to say some black swan event doesn't kill everything in a year. So be careful and don't invest more than you can afford to lose.

As for the coins, you should do your own research. They generally break down along the lines of:

Utility tokens (like a token you must use if you want to use a platform that does rendering, or storage, etc.),

Govenance tokens (those who hold them own the platform, and desicions are made where each token is one vote),

Platform tokens (like ETH, think of them like an OS),

Stable coins (USDC is pegged to the dollar, but there are more interesting and experimental coins that are not pegged to anything yet still stable through economic games),

Security tokens (securities as in stocks - these tokens represent ownership of something, even physical things like real estate), and

Non-fungible tokens or NFTs that certify something as uniqe and authentic.

Some cool blockchain things are:

Defi (decentralized finance), where things like AMMs (automated market makers) give liquidity to tokens by creating pools with incetives for liquidity providers

NFTs, or proofs of ownership of digital content which are programmable and e.g. can automatically give some % of any future transaction price to the creator or can include any set of rights, and

DAOs (decentralized autonimous organizations) which are collectively owned and run organizations, businesses, and even governments.

This is a good video with more technical detail (still very accessible) https://www.youtube.com/watch?v=bBC-nXj3Ng4