Historically, the programming languages designed for education, easy enough to be used with the younger children, as well as popular enough to inspire a fair amount of educational literature, were Basic, Logo, Scratch and Squeak. Similarly Scheme for older college-aged types. Today, Alice and some simplified Python environments might also be suitable.
One might be able to find ancient books for kids on Basic and Logo in a used bookstore.
Assembly language, C (plus variants), and Java were absolutely not designed with learning them in mind. More like some authors force fitted them into textbooks, with mixed results. So I recommend against these if you need or are looking for the easiest intro to learning coding.
Ignore the suggestions here to start with Objective C, unless you turn out to be quite talented.