Here is a nice writeup on what all the keywords on the cards mean.
Source: http://www.hearthpwn.com/forums/hearthstone-general/general-discussion/405-hearthstone-card-keywords
Card Keywords
Keywords in Hearthstone are a word or phrase that appear on a card that are used to indicate that the card possesses a certain attribute or ability. These keywords are used in place of the full explanation of the attribute or ability, and are explained through the usage in-game tooltips. The following is a list of keywords in Hearthstone that you will be on cards, their in-game descriptions, and example cards which make use of the keywords.
Battlecry
Does something when you play it from your hand.
Example: Alexstrasza
Charge
Can attack immediately.
Example: Grom Hellscream
Combo
A bonus if you already played a card this turn.
Example: Edwin VanCleef
Counter
A card that is Countered has no effect.
Example: Counterspell
Deathrattle
Does something when it dies.
Example: Cairne Bloodhoof
Divine Shield
The first time this minion takes damage, ignore it.
Example: Tirion Fordring
Enraged
While damaged, this minion has a new power.
Example: Grom Hellscream
Freeze
Frozen characters lose their next attack.
Example: Blizzard
Immune
Cannot be damaged
Example: Bestial Wrath
Overload
You have {0} less mana next turn. (0=number defined on the card)
Example: Lava Burst
Secret
Hidden until a specific action occurs.
Example: Snake Trap
Silence
Removes all card text and enchantments.
Example: Mass Dispel
Spell Power
Your spell cards deal {0} extra damage. (0=amount of spell power)
Example: Malygos
Stealth
Can't be attacked or targeted until it attacks.
Example: Edwin VanCleef
Taunt
Enemies must attack this minion.
Example: Tirion Fordring
Windfury
Can attack twice each turn.
Example: Al'Akir the Windlord
Source: http://www.hearthpwn.com/forums/hearthstone-general/general-discussion/405-hearthstone-card-keywords
Card Keywords
Keywords in Hearthstone are a word or phrase that appear on a card that are used to indicate that the card possesses a certain attribute or ability. These keywords are used in place of the full explanation of the attribute or ability, and are explained through the usage in-game tooltips. The following is a list of keywords in Hearthstone that you will be on cards, their in-game descriptions, and example cards which make use of the keywords.
Battlecry
Does something when you play it from your hand.
Example: Alexstrasza
Charge
Can attack immediately.
Example: Grom Hellscream
Combo
A bonus if you already played a card this turn.
Example: Edwin VanCleef
Counter
A card that is Countered has no effect.
Example: Counterspell
Deathrattle
Does something when it dies.
Example: Cairne Bloodhoof
Divine Shield
The first time this minion takes damage, ignore it.
Example: Tirion Fordring
Enraged
While damaged, this minion has a new power.
Example: Grom Hellscream
Freeze
Frozen characters lose their next attack.
Example: Blizzard
Immune
Cannot be damaged
Example: Bestial Wrath
Overload
You have {0} less mana next turn. (0=number defined on the card)
Example: Lava Burst
Secret
Hidden until a specific action occurs.
Example: Snake Trap
Silence
Removes all card text and enchantments.
Example: Mass Dispel
Spell Power
Your spell cards deal {0} extra damage. (0=amount of spell power)
Example: Malygos
Stealth
Can't be attacked or targeted until it attacks.
Example: Edwin VanCleef
Taunt
Enemies must attack this minion.
Example: Tirion Fordring
Windfury
Can attack twice each turn.
Example: Al'Akir the Windlord