There are three aspects to be considered with adjectives: 1) Most adjectives go after the noun, but you could also use it before (in some cases it would have a poetic sense) La mujer bonita = La bonita mujer 2) There are some adjectives that change its ending when used in masculine before the noun: Un día malo = Un mal día (therefore, "día mal" is incorrect) El día primero = El primer día (also for bueno/buen, tercero/tercer, grande/gran) 3) There are some adjectives that change the meaning when used before or after the noun: Un gran alumno (a great student) / Un alumno grande (a big student) (here is a list of some other adjectives that change its meaning: https://espanol.lingolia.com/es/gramatica/adjetivos/posicion)

Hi Alyona! I was reading your message and I'd like to help you, but I don't understand your problem, because you can write 'mal día', and also you can write 'día malo'. For instance: Hoy hace un día malo, this sentence means that today we have a bad weather. I hope this helps. If you still have doubts, I can give you more examples,

It's the same as in "buen día" and "el día es bueno" o "el día está bueno", when the adjective is masculine it only gets that "o" at the end when the adjective goes after the noun.

hi dear. , It Happen Because Here on south America we don't talk the adjetive fist Than Subjective, Ever That You want to say Something You may use to Substantive Fist, I Know It Let's Us Crazi In The Starts But after you learn It's Stay easy