Translation:The fall is amazing.
It could also be translated as "Fall is amazing" because Arabic approaches generalizations in a different way than English. In Arabic, generalizations are definite whereas in English they are indefinite. So خَريف مُمْتاز would not mean "Fall is amazing", it would simply be a clause meaning "amazing Fall". To say "Fall is amazing" you have to add in the alif lam and say اَلْخَريف مُمْتاز.