This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
繥 combines 糸 (thread) with 喜 (joy), but the exact historical development is uncertain. It may have originally been a variant of 禧 or 嬉 with a thread-related nuance, but no clear etymology is established.
The left side is thread 糸, and the right side is joy 喜. Imagine a joyful celebration where colorful threads are used to decorate, but the exact meaning is uncertain.
For キ, imagine a key made of thread that unlocks joy: key -> キ, and the thread 糸 brings happiness 喜.