resistance is a price at which there is a large player, or group of market players who wish to sell. so as the market buys and the price hits this level, their selling activity forces the price back down.
ie the price 'resists' going higher.
in currency, if you have shorted a pair, resistance points can be where large market players have orders to go long, and the price 'resists' falling through that level.
support points are the opposite. support is resistance working 'for' you, stopping a price from moving against you. resistance works 'against' you, stopping a price from moving for you.