Leverage determines the amount of money you need in your account so as to be able to trade.
Eg for 1:100 Leverage
Number of Lots X (Size of lot divided by leverage) X $1.1000
1 X (100000/100)x1.1
That is the money needed to buy 1 standard lot (100 000) of USD/CHF at 1:100 leverage. Without leverage you would need $110 000.00 to buy 1 standard lot size of USD/CHF