If you hold a currency position overnight the rollover (swap) will take effect.
Rollover represents the interest paid or earned for holding a position overnight.
Each day at 22:00 London Time (Forex market change time) Price Markets will settle all FX positions by closing the trades at the current market rate and re-opening them at a rate which reflects the interest rate differential.
For example, each trade in the case of Forex involves not only 2 different currencies, but their two different interest rates. If the interest rate on the currency you bought is higher than the interest rate of the currency you sold, this positive differential is taken into account. If the interest rate on the currency you bought is lower than the interest rate on the currency you sold, then you will pay rollover.
For a position held on a Friday or prior to a Price Markets non-business day, financing will be applied according to the number of days until the subsequent Price Markets business day. For example, for a position (held on Wednesday) rolled from a Friday to Monday, financing will be applied for 3 days.
Note that rollovers are applicable to all FX and CFD products.