Ruthi, thank you very much!

It means "as you watch" or "as you look". For example ,magicians will say "I am going to do this trick before your very eyes" it means watch closely and see something happen.

But what does it means - before your very eyes? )) Completely don't understand

It means that the product will make any type of hair look better, even if your hair is very thin, it will be changed and look better.