Probably one of two things, and they're very different.
1) He may mean mining farms. Miners (often big warehouses of machines, hence "farms") add blocks and make it expensive to rewrite history. That secures the network as a whole, not his coins in particular. Nobody's mining protects one person's bitcoin. Whitepaper, section 4 (proof-of-work):
https://bitcoin.org/bitcoin.pdf2) Or someone else is "protecting" (holding) them for him. Then the real question is the one already asked here: who has the keys? Whoever holds the private keys controls the coins; if a third party holds them, he's trusting that party, not Bitcoin.
https://bitcoin.org/en/secure-your-walletIf it's the second and it involved sending crypto to someone to keep it safe, promised returns, or fees to withdraw, the FTC lists exactly that as scam patterns ("no legitimate business is going to demand you send cryptocurrency... not to protect your money"):
https://consumer.ftc.gov/articles/what-know-about-cryptocurrency-scamsWorth asking him which one he meant.