Sewing from a pattern is as easy as followinga recipe for a cake. Most patterns include a key to their abbreviations but if not I'm sure their will be a decoder on line somewhere ;)
Here's my tip don't cut your pattern though, trace over it with some newspapper or tracing paper and cut that. I made that mistake once and couldn't use the other sizes include din the pattern doh.

Interfacing is the stiff webbing type fabric that often goes inside two normal bits of fabric to give some body and stiffness to it. You often see in around that strip where buttons fo ina shirt. You can get iron on interfacing hwich makes life a lot easier.

Good luck, what are you going to make?