Translation:Red, yellow, and orange are fall colors.
An indirect one, the most likely etymology is from červ - a worm. The month when worms are plentiful.
However, the name of the colour might be derived from the same worms:
"Old Czech črvený is from Proto-Slavic čьrvenъ, which is a passive participle of čьrviti (“dye using červec”), where červec is a kind of worm used as a red dye (compare červ (“worm”))." https://en.wiktionary.org/wiki/%C4%8Derven%C3%BD#Etymology