The airnode-abi package is a unique way to encode and decode parameters for use with Airnode. Parameters are provided with encoding types, names and values. The types are shortened and grouped with a version as the "header". The name/value pairs are then grouped and encoded as the rest of the body.
An advantage of encoding parameters this way is that parameters can be decoded natively using the language(s) of the specific blockchain. In the case of EVM blockchains, this means that parameters can be encoded as well as decoded in Solidity (or Vyper), without any additional requirements.