An echo is an Echocardiogram, which is, as stated here, an ultasound of the heart.
Basically there are 3 types:
My guess is that they will do the Transthoracic Echocardiogram. It sounds much more complicated than it is. It is probably the most routine echo they do. Here is a description of it:
"Echocardiograms: Ultrasound waves are transmitted, and their echoes are recorded with a device called a transducer. It looks a little like a microphone. A computer uses the information from the transducer to create moving images on a video monitor. Several types of echocardiograms are available. Each is specially suited for different situations or problems.
-Transthoracic. A technician spreads gel on your chest and then presses a transducer firmly against your skin. You may be asked to breathe in a certain way or to roll over onto your left side. Sometimes, the transducer must be held very firmly against your chest and this pressure can be uncomfortable, especially over your ribs."
Like they said, the transducer they mention looks like a microphone or a short wand that they move over your chest area. It is painless, and not very uncomfortable. Echos record images of the heart.. it determines the heart's functioning capabilities and it measures the size of the heart.
Good luck on the results, I wish you well.