It's programming language used for a few things (open office is written in JAVA for example)
It's safe to update, but to be honest, it's one of those things that appears on a lot of peoples computers when they don't really need it.
I'd personally remove it totally and see if anything stops working, if it does reinstall the latest version, if everything works fine leave it off altogether.
Hmmm, surely the progs you have already installed ought to be capable of running on the java you already have ? Anything new ought to update as required. (Unless they're admitting to a defect and necessary security patch.)