Where does “полочка” come from?

полочка (Russian) comes from Russian -ка, from Proto-Slavic -ьka, from Proto-Balto-Slavic -ikaʔ, from Proto-Indo-European -ikeh₂.

Ancestry of “полочка”, step by step

StepLanguageWordMeaning
1Russian-каnow, just
2Proto-Slavic-ьka—
3Proto-Balto-Slavic-ikaʔ—
4Proto-Indo-European-ikeh₂—
Every word from Proto-Indo-European -ikeh₂ →Every word from Russian -ка →Every word from Proto-Slavic -ьka →