Here's a great site skipping hearts [dot] com that has info on all sorts of things heart related and gives normal cardiac values: http://www.skippinghearts.com/articles/normal-heart-test-values/ about half way down it has EKG/ECG values with links to info etc.
Well, it's not going to make much sense if you haven't taken a class or two in this stuff, but it's an analysis of your EKG strip. Those squiggles you see on the strip, the spikes and dips, represent electric signals put out by various parts of your heart as it contracts. Each electrical segment of the contraction is measured in milliseconds; each has a name (P, Q, R, etc); and in healthy hearts they each have a pretty standard strength or amplitude and duration.
The strength of various signals calculated against each other (all those leads stuck to your chest and your legs) also tells the doc something about the orientation of the heart as it sits in your chest (some people have more vertical ones than others and so on), and about its proportions, too.
So, what you have with all those numbers is the information that at 51 beats per minute, your heart beats a little bit more slowly than is usual (called bradycardia), but that in every other aspect that I mentioned above, it's healthy and normal.