The average person can hold their breath for around 3 to 4 minutes before they have to stop holding their breath and need to breathe.
So you should be able to hold your breath for at least 3 minutes but you might be able to hold your breathe for 4 minutes.
After around 4 minutes you will probably start breathing spontaneously without even trying to breathe because your body will respond and your brain will tell you mouth to open so that you can breathe.
If you hold your breath for 5 minutes or longer then you could cause brain damage and pass out and possibly die so don't hold your breath longer than a few minutes.
If you need to be under water for longer than a few minutes then you should wear a snorkel or wear an oxygen tank to be able to get oxygen and air underwater.