Learn Russian: Нормальный ответ.

Russian doesn't have articles like "a", "an", or "the". A phrase like нормальный ответ can mean "a normal answer" or "the normal answer" depending on the context.

Why does нормальный end in -ый?

The ending -ый is used for masculine adjectives in their basic dictionary form. Adjectives must match the gender of the noun they describe. Because ответ (answer) ends in a consonant, it is a masculine noun, so the adjective takes the masculine -ый ending.

Why is the letter о in нормальный pronounced like an "a"?

This happens because of a rule called vowel reduction. When the letter o is in an unstressed syllable (the stress in this word falls on the second syllable: нор-МАЛЬ-ный), it is pronounced like an "a".

Is нормальный used the exact same way as "normal" in English?

Mostly yes, but it is even more common in Russian everyday speech. While here it means "normal" or "standard" (нормальный ответ), Russians also frequently use it to mean that something is simply "fine," "okay," or "acceptable."