What is mean of .com, .org,.in, .net, co.uk, co.in in a website

Those are just the "domain" names of the website. Most of them don't mean too much, but some have special meanings. ".com" is just the standard default name most websites have. ".org" is used for organisations that don't fit into others (usually noncommercial ones). In practice, anyone can get one of these. ".edu" means that the website belongs to an educational institution.
".gov" means that it is a government website. ".au", ".co.uk", ".jp", and meany others indicate which country the website is based in (e.g. .au" websites are in Australia).