I wanted to add ductfree range hood on a circuit which has GFCI outlet in first position..wanted to check wires so I opened GFCi outlet and found 2 black and 2 white wires...

can some one explain what is the meaning of having 2 white and 2 black wires...total 4? I dont think any of them is ground...

also can I add 2 amp rated under cabinet duct free range hood on this circuit where only other items in circuits is 1.kitchen lights 2. utility room lights