Can I use .intern to have the same effect as .to_s or .to_sym?
my_string = “Hello”
my_symbol = my_string.intern
puts my_symbol

is like:
my_string = “Hello”
my_symbol = my_string.to_sym
puts my_symbol

and vice-versa but .intern can replace .to_s and .to_sym right?

It appears .to_s and .intern do basically the same thing (that is, they make something a symbol). Read this StackExchange for more information. .to_s turns something into a string:

4.to_s#gives "4"
true.to_s#gives "true"
:symbol.to_s#gives "symbol"