This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
枑 combines 木 (tree/wood) with 互 (mutual). The exact historical development is uncertain, but it likely relates to a wooden structure or barrier.
The left side is a tree 木 and the right side is 互, which suggests mutual or reciprocal. Picture a wooden barrier made of interlocking logs that support each other.
For コ, imagine a small wooden コ (child) playing near the barrier: コ -> コ.