It's a verb that second language learners learn early in their development as it's important for them to be able to spell basic words (e.g. their own name, nationality, etc), and ask how to spell new words that they encounter.
It has a conjugated third person form "spells" (/spelz/". It is an ambiregular verb so the preterite and past participle can be a regular verb, i.e. "spelled" (/spelt/ or /speld/); and in British English this can be an irregular lexical verb spelt "spelt" (/spelt/). The -ing form is "spelling", which as a noun is an important aspect of written language.
Spell, with different etymology, also has a different meaning, in magic, e.g. "to case a spell". It also can mean a short period of time.