The default is 5:00 Min as shown in New Song Setup, however the song won't stop at that time, Studio One will additional time as your recording progresses.
In the song itself, the timing is set to Bars by default. You can click on the dropdown and change it to Seconds to view the length of your song in Minutes and Seconds.
When you export your song, you'll need to set your Export range so Studio One knows what length to bounce.