First, make two lists from your database. Something like:
cursor = con.cursor()
cursor.execute("SELECT * FROM traffic")
#Retrieves data from SQL
rows = cursor.fetchall()
Month = list()
Traffic = list()
for row in rows:
Month.append(row['Month']) # guesswork - what does a row look like?
Traffic.append(row['Traffic'])
Then, now you have two python lists, you can make a plot thus:
>>> r.plot(Month,Traffic)
rpy2.rinterface.NULL
You maybe want lines:
>>> r.plot(Month,Traffic,type="l")
rpy2.rinterface.NULL
You maybe want nice labels:
>>> r.plot(Month,Traffic,type="l",xlab="Month",ylab="Traffic")