This is the 12654th most frequent Russian word.
коньком
The Russian word "коньком" means "by means of a skate" or refers to "one's strong point/specialty" depending on context.
Here, "коньком" metaphorically means 'someone's forte or specialty'.
Катя выступает своим коньком в фигурном катании.
Katya performs her strength in figure skating.
Here, "коньком" in its root form is part of the phrase indicating ice skating (using blades of ice-skates).
Мальчик катается на коньках по льду.
The boy is skating on the ice.
In this context, "коньком" literally refers to an ice skate as a tool used for cleaning.