Yes, you can have multiple trades open simultaneously.
How many trades you can have open depends on your pips available.
Example:
You have 50 pips available and decide to open three trades:
Trade 1: EUR/USD with a 15-pip SL
Trade 2: GBP/USD with a 20-pip SL
Trade 3: USD/JPY with a 10-pip SL
After these trades, you’ve used up 45 pips (15 + 20 + 10 = 45), leaving you with 5 pips available for additional trades.
To open another trade, you need to either reduce the SL on one of your existing trades or ensure the new trade’s SL doesn’t exceed the 5 pips you have left.