For long hair it helps with combing. Just like the old silicone spray for ballpoint mice, it reduces friction with the comb.

Most lotions contain dimethicone, a silicone relative.

They both work by being moisture barriers, preventing moisture loss (for hand lotion).

As someone who struggles with skin issues, I don’t even bother with lotions that don’t have dimethicone, they’re practically useless for me.