It's sugar + amino acids. The sugar is useful if your doing an organic grow and want to feed beneficial microorganism like erricoid mycorrhyzae, endomycorrhizae, and ectomycorrhizae. It's not as useful when your using chemical fertilizers (e.g. Advanced Nutrients Sensi or their 3 part formula) since these concentrated nutrients tend to kill the microorganisms faster than your able to replace them. The amino acids on the other hand act like multivitamins, helping to improve the plant's overall immune system.
Neither one of these have been proven to significantly improve yield or taste for any plant (let alone cannabis) but they are becoming popular in the cannabis growing communities. Whether they work or not is up for debate, but at the very least they don't seem to do any damage. So if you have money to burn, have at it.