If you want to see what upcoming or past appointments a specific patient has you can always run an export report, but generally it's easiest to just look this up from the patient dashboard. If you just want to see the next and last appointments that the patient has scheduled, just hover over the Scheduling link at the top of the patient's dahboard page and you should see entries for their next and last scheduled appointment:

If you want to see a patient's entire schedule history (both past and future) you can just hover over the Scheduling tab again and select the "Show Patient's Task and Schedule History" option, which will launch a window that includes this data: