Monthly Recurring Revenue (MRR) is the predictable recurring revenue earned from subscriptions in a specific period. As the name indicates, MRR is calculated for a monthly "duration". The MRR amount shown on the dashboard is a total of all your subscriptions' MRR.

For example,

In a monthly plan, if you have 10 customers each paying you $100 per month, then the MRR is $1,000.

In a yearly plan, if $1,200 is paid annually, then the MRR is normalized as $100 per month. 

NOTE: MRR is not the same as “payment received”. It is a predictable recurring revenue from the current value of your subscribers. This makes MRR a prominent indicator of your business performance, since signups, upgrades, and churn will impact this metric.