Exercise (or Strike) Price
The exercise (or strike) price is the fixed price at which the option can be exercised.
So if you buy a call option which has a strike price of 50.00, then you have bought yourself the option to buy the asset at a price of $50.00.
However, in the real world you only want to exercise your right to buy that asset at $50.00 if the underlying asset is actually worth more than $50.00 in the market. If the underlying asset is below $50.00, there is
no point in doing so because you'd be exercising your right to buy the asset for $50.00, when it's only actually worth, say, $40.00. No-one would do that because they could buy it for $40.00 in the market.
This leads us to the words "before a predetermined date"