Isabel is an alien/human hybrid. The canon explanation is that human DNA was mixed with her alien essence (Whatever the hell that is) to create her and the other aliens. Their powers are human though. Basically alien technology allowed their brains to be developed to their fullest potential. They're what humans would be like after a few more eons of evolution.

Isabel can manipulate things on molecular level. By that I mean heat them up, cool them down, change their color, change their taste (ketchup into mustard). She can remove stains from clothing.

She can start fires, basically small sparks that can ignite something.

She's telekinetic, able to move objects with her mind and if stressed enough, she can blow things up.

She can create a shield around herself and anyone nearby. It will block anything from reaching her/them.

She can make a CD play music without using a player.

And I think that's it for the moment.