expression, noun
chance to show one's skill; opportunity to demonstrate one's ability
Used when a situation allows someone to display their expertise or talent. Often implies a moment where one's true ability is tested or can shine.
この難しい交渉こそ、彼の腕の見せ所だ。
This difficult negotiation is exactly the chance for him to show his skills.
料理が得意な彼女にとって、パーティーは腕の見せ所だった。
For her, who is good at cooking, the party was an opportunity to demonstrate her ability.
From 腕 (skill) + の + 見せ所 (place to show). The phrase literally means 'a place to show one's arm/skill'.