Wallet REST API: REST-RPC-API
Bcoin maintains a wallet database which contains every wallet. Wallets are not usable without also using a wallet database. For testing, the wallet database can be in-memory, but it must be there.
Wallets in bcoin use bip44. They also originally supported bip45 for multisig, but support was removed to reduce code complexity, and also because bip45 doesn't seem to add any benefit in practice.
The wallet database can contain many different wallets, with many different accounts, with many different addresses for each account. Bcoin should theoretically be able to scale to hundreds of thousands of wallets/accounts/addresses.
Each account can be of a different type. You could have a pubkeyhash account, as well as a multisig account, a witness pubkeyhash account, etc.
Note that accounts should not be accessed directly from the public API. They do not have locks which can lead to race conditions during writes.