Water is a great solvent. It’s neutral and doesn’t provide any strong positive or negative effects. It just helps components to mix better and to transport active components.
Lactic Acid is the most popular and the least aggressive acid among all the AHAs. Unlike Salicylic and Glycolic acids which can irritate your skin, Lactic Acid will hardly cause any problems. The combination of its soft action and effectiveness makes it a real brilliant. It exfoliates dead cells, makes the skin tone even, clears pores, kills bacteria, moisturizes the skin and helps to keep water, helps the cells to produce Hyaluronic Acid. It also works as a strong antioxidant and anti-aging component.
It's a great acid for getting familiar with the world of AHAs. If you want to start using "fruit acids" but struggling for some reason, try to use Lactic Acid first. If your skin accepts it well, you can try stronger acids.
PEG-40 Hydrogenated Castor Oil helps ingredients to mix better. It has nice cleansing activity helping to remove sebum and dirt from the surface of your skin. It's also responsible for making soft foam in soaps, shower gels, etc. Despite it having "PEG" in the title, it's considered to be safe.