The electrical box has two circuits, each with black (hot) and white (neutral) wires. One black wire was wire-nutted because someone in the past decided that the circuit was no longer needed. I checked a combination heater/fan; it requires two circuits, one for the fan and a second for the heater. If you're installing a simple fan, just reattach the wire nuts to the unneeded wires, and attach the hot, neutral, and ground wires to the new fan.

So i can just wire nut that black wire and nut the two whites and install nornally and i should be good?

The black plug plugs into an outlet in the ceiling electrical box, right? Where does the rectangular, white connector go?

Thats a pic of the old fan. the new one will have wire nut connectors

Playing with electricity without the proper tools is somewhere between dangerous and inelegant.

Consider the possibility that one Romex cable goes to the breaker box and the other goes to the switch. Then it is reasonable for the blacks to be wired together, the white from the switch should be marked black and tied to the black fan wire, and the white to the breaker box to the white fan wire. This requires determining which cable goes to the switch. If the switch box has only one Romex cable going into it, then this option is likely.

Another possibility as noted above is that power from the breaker box originally goes to two switches, one for a fan and one for a light, and only one of the two cables shown should be used. This would depend on what switch box configurations were in use in the room.