Picture a long string of letters and numbers, that's your private key. Now split it into 5 and give the shares to 5 different devices around the world. Imagine how complicated it would be for a hacker to assemble these pieces.
There are 5 parties which form a network to protect your wallet. These are: you (1), Gridlock guardians (2) and your personal guardians (2). Invite 2 friends as guardians to complete your network.
Completing transactions requires 3 of these devices to be online, which is normally you and Gridlock. This means the app can function without personal guardians, but your wallet would be more at risk.
Security is the most important thing in crypto - without it, your funds are vulnerable. This is why completing guardian setup is your first priority!