Can you tell me what the button on the left hand of handlebars is for ,when pressed a red
Arrow/triangle shows on dashboard

[2015 Z Force 800 53/Trail EPS]

Can you tell me what the button on the left hand of handlebars is for ,when pressed a red
Arrow/triangle shows on dashboard

That's the Diff-loc override. When in 4wd and the diff is locked, speed is limited for safety. Sometimes you need full power to get out of something...that's what the button is for.