I started my career as a UI developer.. My 1st task is too make HTML5 to work in all browser especially IE family... But i heard HTML5 wont support mostly in IE.. My question is...

how to Make HTML5 work in old versions of Internet Explorer ??
What are roles and responsibilities of UI developer??
What are language i have to learn except jquery, css3 and html5 to shine as UI developer ??

Well, if you just started a career in UII developing, you should probably know what their responsibilities are by now.

Here is a little info on a UI developer: http://programmers.stackexchange.com/questions/58246/who-can-call-themselves-a-ui-developer

I know that i read somewhere where a ui developer should know basically any web language.

I found this to help you answer your original question about html5 and IE:

If the browser doesnt support HTML5 elements, then it doesnt support it. However, that doesnt mean that an older version of IE cannot load a web page with an HTML5 doctype.

<!DOCTYPE html>

that just means that if you expect to support earlier versions of IE, you shouldnt expect certain HTML5 elements to work as expected. Other elemnets like <input /> that are support across different version of IE, may not support the newer HTML5 input attributes. Say for instance the input type of "number" or "range". In IE, you get a standard text box, where in other browsers, you get the appropriate HTML5 component.

Try visiting this link with IE and Chrome so you can see the difference:
HTML5 Form Input Types

Internet explorer is typical browswer if its not supporting html 5 you are not supposed to use new tags.