Cryptocurrency wallet is used to store the Credentials used to be able to make cryptocurrency transactions as, typically, the cryptocurrency is on and inseparable from the underlying blockchain or other Distributed Ledger Technology
Cryptocurrency wallet allows you access to your Private Key, which makes it possible to digitally sign a transaction and write it underlying blockchain or other Distributed Ledger Technology, effectively spending or transfering the associated cryptocurrency.
There are many types pf Cryptocurrency wallets:
Cryptocurrency wallets may be run locally or as Software as a Service where the Cryptocurrency wallet Service Provider "hosts" the wallet.