That datasheet doesn't contain any information about the dual hall sensors, other than it's an option you can order. Where do the names "data1" and "data2" appear?
Given those names, it's likely to be an encoder. That means the two signals go high and low in a pattern which allows you to determine which direction it's moving. This page on the Arduino playground may be helpful.
The encoder will give you relative position. Starting from anywhere you can count steps up or down from that point. You need one more piece of information to get the absolute position: you need a starting point.
One common method is to drive towards one end for a period of time longer than it would take to get to that end. The motir drives into the end-stop. Now you know it probably is at the stop. (In the actuator you have, I think it has switches inside to halt the motor and stop it burning out.)
The next-most common method is to put your own "home" switch just before the physical end-stop. Then you get a more direct indication of where it is without slamming into the end at full speed.
But "home" doesn't have to be at the end. It may be in the middle or in the normal parking position. Then you update the absolute position any time the nornal operation passes over the switch.
