I am starting to learn Jess and I want to know if there is in Jess an equivalent operation to the % in Java? By the way, there is something in the internet that you recommend to learn it?
For example:
(bind ?z (Symbol 5 7))
?z = 5
(bind ?z (Symbol 49 7))
?z = 0
The Jess function you want is
(mod <numeric-expression> <numeric-expression>)
As for learning Jess, there Earnest Friedman-Hill's book (not on the internet, AFAIK) is still the best, I hear. But the manual that comes with Jess is very good, and you can learn a lot from that.
Since Jess is a Lisp dialect, you can learn from any tutorial on Lisp. Then, browse the reference, just to get an idea what is available.