Hi,i'm Gary

[frater secessus]

...the guy i asked said this could handle  about 1000 unique visitors,whatever that mean

"1000 Uniques" is a term of art that roughly means something like "1000 different people" in a given period, typically per day or month.  Usually judged by IP address and/or user agent.  <-- everybody click there if you want to see how your browser identifies itself. 

The issue isn't as clear as it might seem for several reasons:

• individuals might use several different browsers, as with power users
  
• individuals might share the same browser, as with a home pc everyone uses
  
• for performance or other reasons sometimes groups of users come from the same IP, as with proxies
  
• sometimes browsing clients are not human at all, but are spiders/bots cataloging content for search engines, as with Google or Bing.  Setting a robots.txt file in the webserver's document root will provide instructions to well-behaved spiders.  For example, you might want to block searchbots early on to protect your bandwidth. 
  
• and weirder stuff
  

In the business of web hosting "uniques" are used because the term is common among marketing and social media types that usually do the web stuff.  Ad people talk about things like "unique impressions" in print and multimedia.

Functionally, the reason this matters is that repeat visitors consume CPU/socket/bandwidth resources differently (and usually more lightly) on a request-by-request basis than "new" uniques.  Has to do with caching, mostly, but also cookie setting for folks that don't already have them, etc.

Of course, I could be making this stuff up.  I'm going eat my pretzels and sit quietly now.