Where does “reča” come from?

reča (Molise Croatian) comes from Serbo-Croatian reč, from Proto-Slavic rěčь, from Proto-Slavic rěk-, from Proto-Slavic -ь, from Proto-Indo-European -is — Forms nouns from verbs.

Ancestry of “reča”, step by step

Step	Language	Word	Meaning
1	Serbo-Croatian	reč	word
2	Proto-Slavic	rěčь	speech
3	Proto-Slavic	rěk-	—
4	Proto-Slavic	-ь	Forms nouns; From adjectives; From participles
5	Proto-Indo-European	-is	Forms nouns from verbs

Every word from Proto-Indo-European -is →Every word from Proto-Slavic -ь →Every word from Proto-Slavic rěk- →