"Resource Leak: '<var_name>' is never closed" in Java. What does that mean?

Question

So i'm just starting out in Java and i've been having these "warning" messages;
Scanner scal= new Sacnner(System.in);
"Resource Leak: 'scal' is never closed"

I still can compile but i can't seem to understand what's happening.

Answer 1

scal.close() at the end of using it.

Answer 2

Thanks a lot!!