Can anybody explain the '-' in a 2-D creation code?

[fl]

On Thursday, June 25, 2015 at 6:24:07 PM UTC-7, Mark Lawrence wrote:
> On 26/06/2015 02:07, fl wrote:
> > Hi,
> >
> > I read Ned's tutorial on Python. It is very interesting. On its last
> > example, I cannot understand the '_' in:
> >
> >
> >
> > board=[[0]*8 for _ in range(8)]
> >
> >
> > I know  '_' is the precious answer, but it is still unclear what it is
> > in the above line. Can you explain it to me?
> >
> >
> > Thanks,
> >
> 
> Lots of people could carry on explaining things to you, but you don't 
> appear to be making any attempt to do some research before posing your 
> questions, so how about using a search engine?
> 
> -- 
> My fellow Pythonistas, ask not what our language can do for you, ask
> what you can do for our language.
> 
> Mark Lawrence

Excuse me. On one hand, I am busying on cram these Python stuff quickly for
a position. On the other hand, the search seems to me needing a little 
skill to get the goal I hope. I would really appreciate if someone can give
an example on what phrase to use in the search. I am not a lazy guy.
Thanks to all the response.