Multisig security technology, integrated by Bitso through BitGo is a type of security for wallets that need 2 out of 3 private keys in order to make a Bitcoin transfer. This technology provides a much higher security for safeguarding your bitcoins.
An example of how this technology protects your Bitcoins is: "An attacker obtains access to the Bitso website and wants to withdraw all the users’ Bitcoins. It simply could not do it since to make a transfer it needs at least another private key that is safeguarded by our BitGo multisig security supplier."
You can recognize a multisig address by the number it starts with, the bitcoin addresses that do not integrate this security start with a “1” while the addresses integrating the multisig technology start with a “3”.