Thru-axles are larger in diameter than traditional axles. They allow for a stronger and stiffer hub and help disperse braking forces. Thru-axles thread directly into the frame or fork through a hole, instead of sliding into a slotted dropout. Follow the steps in this quick video to become a thru-axle expert.
Removing a thru-axle:
Open the lever and line it up in the cutout notch (if available).
Turn counter-clockwise to unscrew, holding the wheel steady.
Pull the axle out, releasing your wheel.
When reinstalling your wheel, pay careful attention to slotting your brake rotor between the pads in the caliper.
With the hub lined up with the axle hole, slide in the axle.
Thread the axle in (clockwise) while opening and closing the lever, looking for resistance from the cam. When you meet resistance halfway, stop threading and close the lever. This should take enough force to leave a slight imprint on your palm.
The final position of the lever can be adjusted by rotating the axle nut. You can access this nut by backing out the axle a few rotations and pushing. You can rotate the nut and make sure your lever can fully close.