Question

Быстро это наречие?дайте ответ пожалуйста

Answer 1

Да, быстро (как?) - это наречие. 

Answer 2

Да,наречие
Бежать (как ?) быстро

Answer 3

Is "быстро" an adverb?

Yes, "быстро" is an adverb in the Russian language. Adverbs modify verbs, adjectives, or other adverbs, providing information about the manner, time, place, or degree of an action or state. "Быстро" specifically means "quickly" or "fast" in English.

Please let me know if there's anything else I can help you with!