The word “information” is an uncountable noun (also called mass noun) in English, just like “smoke” or “rice”. This means that it is treated as a certain kind of “substance” or “matter”, not as an object.
As a result, it does not make sense to say “an information”. You should say, for example:
If you want to stress that you talk about a specific “unit” of information, you can use the word “piece” (just like you would use the word “cup” for rice):
Since it’s uncountable, “information” does not have a plural form and is combined with “little” and “much” rather than “few” and “many”:
When you want to express that you have a small amount of information, the most natural way is to use “some information”. Saying “a little information” is possible but much less common: