Cyrillic isn't only for Russian; it's also used by other Slavic countries like Bulgaria and Serbia. The Bulgarian language also uses the Cyrillic script.
Pro Tip 2/3
Visual Distinction
Cyrillic letters can look similar to Latin ones but often have different sounds. The Cyrillic letter 'P' is pronounced as 'R' in the English.
Pro Tip 3/3
Not Phonetic
Each Cyrillic letter represents a specific sound, making reading predictable once you learn it. Once you master Cyrillic letters, you can read words aloud confidently.