Certified GKH Gardening Expert
Rooting hormone is a substance you can buy that has fungicide and plant hormones. The fungicide helps to keep away rot and the plant hormones will encourage the cutting to grow roots. It is available at most nurseries, including those outside big box stores.
Soilless mix typically refers to potting soil. It means a planting substance that does not have soil, as in the stuff the ground is made of, in it. Instead, it is made of plant based material, like peat moss. Soilless mix does not compact down like soil does, which is why it is good for rooting cuttings.