apache - htaccess i don't know what the code mean -

i have site, it's working until today give me error 500 open htaccess , find code

<ifmodule mod_rewrite.c>  rewriteengine on  rewritecond %{http_host} ^www\.adminapi\.* [or] rewritecond %{http_host} ^adminapi\.* [nc] rewriterule .* http://www.*mysitehere*.com/adminapi [l]  rewriterule ^adminapi - [l]  rewriterule    ^$ app/webroot/    [l] rewriterule    (.*) app/webroot/$1 [l]  </ifmodule> 

so remove code htaccess site didn't work before

can me understand code