A blockchain transaction is a transfer of value from one address on a network to another. A user creates a transaction in their app, and it is then sent out to the blockchain. The user's transaction then sits in a "mempool" of other pending transactions, where it waits to be "mined". Once enough miners confirm the transaction, it is stored forever in a block. (by design, blockchain transactions are permanent)
The block contains a batch of transactions, and has specific time and size limits for how many transactions will fit in it. Once the block time is up, or its maximum amount of transactions has been reached, the block gets added to the chain, and the next block iteration begins.
Each transaction can be viewed on a "block explorer". Here is a list of block explorers for each network on 1inch:
Ethereum Mainnet: https://etherscan.io
Binance Smart Chain: https://bscscan.com
Here are all of the following types of transactions possible with 1inch: