All programming languages have things in common with the English language. Where the analogy is close, J tends to use English language terms in preference to terms used in math and other programming languages.
You could, as in other languages, say line of code, but in J you tend to say sentence instead. Similarly you could refer to the + function, but you usually say verb.
Some English language terms used in J are: alphabet, word, sentence, verb, noun, adverb, and conjunction.
There are several reasons for this approach. One problem it deals with is the plethora of related, but subtly different, uses of traditional terms in math and numerous programming languages. For example: function, subfunction, operator, program, routine, and subroutine are all used in slightly different ways in different programming languages. Rather than inherit this confusion, J adopts its own terms, and defines them precisely within its context.
Using English terms gives you a good idea of what the general meaning of the term is in J. In addition, using natural language terms encourages and facilitates taking the English statement of a problem and more directly writing the corresponding J sentences.
The use of the J terms is encouraged, but certainly isn't mandatory, and using the term function instead of verb is quite OK.