First of all, hairpin lace is a knitting technique using a crochet hook and a hairpin lace loom, which consists simply of two parallel metal rods. To use the loom, you wrap yarn around the loops to form prongs, and eventually get a delicate lacy pattern.
You can use the hairpin lace technique to create a number of different crochet projects, including scarves, baby blankets, and clothes. Watch the tutorial for the instructions. This is the left handed version.