To see if your client has replied to their text message and what they have said, you have a few options.
Firstly, you can check in their client profile under Scheduled Bookings or Booking History:
If your client hasn't replied, it will look like this:
You can also check in your Activity Feed in the top right corner of your calendar, by clicking on the bell:
Here you will find client responses to text reminders underneath their name as well as the message that was sent to them.
Confirmations will have a green icon:
Any replies that aren't a simple "Y" are flagged with a yellow icon in case there's more information you need to see:
And cancellations will appear with a red icon: