data = subset(data, select=c(Date, Name, Type, Status, Gross, Fee, Net, From.Email.Address))
data = subset(data, Type != 'Withdraw Funds to a Bank Account')

d = strptime(data$Date, '%m/%d/%Y')
mon = strftime(d, format='%y-%m')

sums = tapply(data$Net, mon, sum)

barplot(sums, main='Paypal net by month')

aggregate(data$Net, list('month'=data$mon, 'type'=data$Type), sum)

Use with output from https://history.paypal.com/us/cgi-bin/webscr?cmd=_history-download

plot and aggregate paypal report

R