Yes, for 30 minutes. When your customer puts a place, a night or a time slot in their basket, the shop holds it while they pay: nobody else can take it.
And after 30 minutes?
If the basket has not been changed or paid, the places become free again for other customers. At checkout, the shop checks again that everything is still available: your customer never buys a place that no longer exists.
After the order
An order keeps its places, even when it is paid by cheque or bank transfer and not settled yet. If you cancel or refund it, the places are freed automatically.
The result: never a place sold twice, whether for a class or a holiday home.
See also: How do I avoid double bookings for a holiday home?, What happens when a session is full?