Fetching details from the dictionary...

knack; skill; trick; secret; know-how; the ropes; hang
bone; skeleton
cremated remains (esp. the bones); ashes
この仕事のコツを教えてください。
Please teach me the knack of this work.
料理の腕を上げるには骨が折れます。
It takes effort to improve cooking skills.
骨を掴むまで時間がかかりました。
It took time to get the hang of it.