If you have lived in muslim environment, you may have heard prayers including subah allah “سبحان الله”
there is many adjectives which are used to present quality and nature of our supreme lord, allah, such as:
akbar اکبر -> allahu akbar -> god is the greatest
subhan is another adjective to introduce a quality of allah,
subhana allah سبحان الله,means allah is pure, immune and away from any kind of evil, it means any ill or evil adjective is all away from allah and never such traits would belong to almighty allah.
 سوره مؤمنون: آيه 91.
 اصول کافي: ج 1 ص 195 ح 10، معاني الأخبار: ص 9، بحارالأنوار: ج 90 ص 177 ح 2.
 اصول کافي: ج 1 ص 195 ح 8.