and is a primitive that allows us to combine two true-false statements into one single statement that is true if and only if both statements are true. 
For example, if we wanted a turtle to eat only if (A) they were hungry and (B) if there was food on the same patch, we could say:
if my-hunger-level > 100 and food-here > 0 [
  eat-food
  set my-hunger-level 0
]
Things to keep in mind when using and:
and primitives in the same conditional primitive such as if color = red and size > 3 and xcor < 0 [ ... ] or ask turtles with [hunger > 1 and food < 1 and money > 10 ].and itself does not do anything; you should use it within a conditional statement such as if and if-else or other primitives that require true-false values such as while. In the model example below, we use and to generate a river down the middle of our world. A patch turns blue if and only if its x-coordinate is both to the left of (width / 2) and to the right of - (width / 2), otherwise, it remains a green patch.
Once you mastered the and primitive, don't stop there. Check out the resources below to improve your NetLogo skills. 
and primitive:ifCarries out a provided set of rules (code) if a given condition is true. Does nothing if a given condition is false.