Pixel Bunyip

I was just wondering what are the licence terms on those types of Wordpress Themes.
Under what licence are they distributed? Can they be used for commercial purposes? Basically, my question is – if a theme is free, what am I allowed and not allowed to do with it?

I would like to know as much as possible

Thanks.

They are free to use, modify, redistribute for free. You can’t charge money for themes from wordpress.org