What kind of information give me a LED of port on a switch or Router?
How long is a piece of string?
It depends on the router/switch/module type as to what each LED means.
On a basic, single RU, single unit switch, the port LED's usually indicate connectivity, speed or duplex - but may indicate other things, depending on the position of front panel pushbuttons (2950's, for example, toggle through several different status displays using a front panel "mode" push button).
What kind of device are you asking for information on?