What is the purpose of “Getter” methods????????

So I'm in school for computer science and we are learning about classes(in python more specifically). I would say that I'm an intermediate level programmer and I've worked with classes before but now they are telling me to do something I've never done

Usually, when I work with classes and I want to get a value, I just call the value by name i.e.foo.val but now I'm being told that this is bad practice and I should be writing getter methods.

class ClassName: def __init__(self, val1, val2): self._val1 = val1 self._val2 = val2 def getVal1(self): return self._val1 def getAccountNumber(self): return self._val2 

What I really would like to know is what is the benefit of using a getter method as opposed to just getting the variable by name