When a Machine-Type monster you control is destroyed by battle and sent to the Graveyard while this card is face-up on the field, you can add 1 Machine-Type monster with 1000 or less ATK from your Deck to your hand.
It can work well with union monsters since Heavy Mech Support Armor lets you special summon a monster from your graveyard. Otherwise, it can provide some support for other deck types that uses low level machine monsters.
Since it only works when your opponent destroys another machine type monster you control while Biofalcon is on the field, your opponent will most likely want to destroy it first instead of trying to attack your other monster(s). You can either use Staunch defender to shift the focus, or use defensive cards to protect itself.