Where does “ясненько” come from?

ясненько (Russian) comes from Russian я́сно, from Russian я́сный, from Proto-Slavic ěsnъ, from Proto-Slavic ěsknъ, from Proto-Balto-Slavic áiˀšknas.

Ancestry of “ясненько”, step by step

StepLanguageWordMeaning
1Russianя́сноclearly
2Russianя́сныйclear, bright
3Proto-Slavicěsnъclear, bright; clear, serene; clear, lucid,...
4Proto-Slavicěsknъ—
5Proto-Balto-Slavicáiˀšknas—
Every word from Proto-Balto-Slavic áiˀšknas →Every word from Proto-Slavic ěsknъ →Every word from Proto-Slavic ěsnъ →