This is the 2055th most frequent Turkish word.
yayılan
"Yayılan" means "spreading" or "dispersing" in English.
The word 'yayılan' is used as an adjective form derived from the verb 'yayılmak' (to spread) and describes the fires that are spreading.
Ormanlık alanlarda yayılan yangınlar, doğayı tehdit ediyor.
The fires spreading through the forested areas pose a threat to nature.
'yayılan' here also acts as an adjective describing the illness that is in the process of spreading.
Pandemi sürecinde hızla yayılan hastalık, birçok insanı etkiledi.
The illness spreading rapidly during the pandemic affected many people.
In this sentence, 'yayılan' modifies 'güzel koku' (pleasant smell), indicating the action of the scent dispersing.