Touch refers to the way the brush touches the surface or more generally the surface that remains after the paint is applied. The following terms can describe the way the paint is applied, watery, wash, impasto, scumble, thinkly, oily, dry, buttery, and thinly.
Touch can be an extremely important expressive element when making a painting. I encourage you to experiment and think about the method that you connect with and helps you to express you and or your ideas. Below are some examples of paintings with a touch that is more visible and expressive.
I know it is hard to see the way the paint has been applied in photos, as I talk about here, it is important to see works in person. Hopefully these images can at least give you a glimpse of what the surface is like and then I encourage you to look more closely next time you go to a museum.