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I'm quite certain you're speaking of an air-gapped wallet setup, where the offline/air-gapped part keeps the private keys safe and never has contact to online internet. The air-gapped part thus is unreachable for malware or other nasty things.
Such a setup has a watch-only wallet part (the watch-only wallet doesn't have private keys and thus can't loose those to malware) which is online to broadcast signed transactions and of course receive updates on transactions of the wallet's addresses.
Such an air-gapped setup with an offline "cold wallet" that holds and secures the private keys and an associated online watch-only "hot wallet" without private keys (it has only the extended public master key to generate all addresses of the wallet) is very secure.
It's less convenient than a decent hardware wallet but offers very good security if handled properly and keeping the cold part always offline.
You should be able to find more about it with search keywords "air-gapped software wallet".
