It sounds like someone is playing a card game. A 'hand' is the set of cards that you are given by the 'dealer' who hands the cards to players at the beginning of the game. If you get a 'good hand', you are in a powerful position in the game. A 'bad hand' means you have a low scoring set of cards. We can use this metaphor widely to talk about life. If someone was born into a poor family, for example, we might say they were 'dealt a bad hand' in life. From your sentence, it seems the player in the game does not have a very good 'poker face'. This means his facial expressions reveal whether the cards he has are good or bad. This information should be kept secret, as the other players could use it to their advantage! Hope this helps Yousef!