palm of one's hand
Literal meaning: the inside surface of the hand. Often used in physical descriptions.
He held a small stone in the palm of his hand.
skill; control; hidden intentions
Figurative uses: one's ability or technique (sense 2); having something under one's control or in one's grasp (sense 3); concealed plans or cards (sense 4). Common in phrases like 手の内を見せる (reveal one's hand) or 手の内にある (be within one's control).
He doesn't easily reveal his true intentions.
In a match, it's important to read your opponent's strategy.
The company is under his control.
one's hand (in card games or mahjong)
Domain-specific use in mahjong and card games: the tiles or cards a player holds. Also used metaphorically in game contexts.
I got a good hand in mahjong.
Standard kanji spelling; high priority in news and frequency lists.
Kana spelling is common in everyday writing, especially when the intended meaning is figurative.
Compound of 手 (hand) + の (possessive particle) + 内 (inside). The literal meaning 'inside of the hand' extended to figurative senses of skill, control, and hidden intentions.