The term is generally used only during tournament play, and virtually never occurs in real life - indeed, being blinded off is so unattractive a prospect that players will play virtually any hand by pushing all in before they end up losing the rest of their stack by just paying the blinds.
Players who get blinded off (or who get close to being blinded off) give themselves no chance to win - they have essentially surrendered the tournament. A player cannot win a tournament by passively waiting for good cards and never playing a hand; eventually, hands must be played in order for the player to get a chance to double up and head upwards in chip count.
Less drastic meaning Edit
Occasionally, the term blinded off will be used to describe a less drastic situation: what happens to a player at a tournament when the player is not physically in their seat for one or more hands - their blinds are placed into the pot just as if the player was there, but the player is unable to actually play the hand. This results in the player's chipstack essentially being reduced by the size of the blinds as they pass by the player's position.
This procedure can be called "being blinded off", but when used in this sense the process does not necessarily mean the player is losing all of their chips or losing the tournament. Indeed, some players leave tournament play for some periods of time as part of their strategy (or to recover from lack of sleep, or from illness) and are well aware that the blinds will be deducted from their chipstack every time they pass - but are willing to pay that price for whatever advantage the player is trading it for (e.g. more sleep or a mental rejuvenation).