* It's a misspelling. Perhaps you meant a similar word like "Islami" or "Islam," which refer to Islam.
* It's a local or regional term. The word might be used in a specific geographic area or community, but it's not widely known outside of that context.
* It's a technical term. It could be related to a specific field or area of study.
To get a more accurate answer, please provide more context or information.
For example:
* Where did you hear or see the word "Istelam"?
* What was the context or the surrounding text?
* What language is the word from?
With more information, I can help you understand the meaning of "Istelam."