Some basic definitions

One problem a new lifter has is dealing with the terminology of lifting. Here are a few definitions to help out.

The first two go together:

Rep - A repetition; one complete execution of a given exercise. For example, in a squat, a repetition involved squatting down and then standing back up. If you see "5 reps" you know this was 5 complete repetitions of that exercise. Sometimes reps are expressed in a range, as in "8-12 reps." This is seen on workout plans that call for choosing a weight you can do for at least the lower number of reps, but preferably less than the higher number.

Set - A group of repetitions. A "set" typically begins when you start the first repetition, and ends when you finish the last one. How long you can rest between repetitions and still consider it a "set" is debatable. Generally, if you're taking more than a short break to enable to next rep, the set has ended. There are many variations of sets, but that's the basic version.

Set/Rep notations - If you see "3 sets of 10 reps" you know this plan calls for doing 3 sets, each of which is 10 repetitions, resting between sets. Sometimes this isn't so clear, however. You may see "3x8-12" and it's clear this is 3 sets of 8-12 reps. On the other hand "10 x 3" can be 10 sets of 3 reps" (probably heavy work!) or 3 sets of 10 reps (a lighter weight, done for more reps). But some people record the weight of the reps, as well, and there isn't a clear consensus on which one comes first. You may see 225x5x3 for 3 sets of 5 reps of 225 pounds, or you may see 3x5x225 for that same workout. These sets at your goal reps and goal weights are called work sets. Sets you do before the work sets to warm up your muscles and practice the exercise are called warmup sets. Sets you do with a lower weight to get ready for your
If you do all of your work sets at the same weight (like the example 3 x 5 x 225) this is referred to as straight sets or sets across.

#RM or # rep maximum - # rep maximum (abbreviated #RM) is the maximum number of repetitions you can do at a given weight. For example, if you can press 135 pounds as many as 5 times but not 6, 135 pounds is your 5RM. If you can press it only once, it's your 1RM. Normally a low number is chosen to express your strength - you'll rarely see anyone crowing about their 15RM or 25RM. Your #RM is usually your tested maximum, although there are calculators that can attempt to predict your given #RM from another #RM. If someone tells you their 1RM, it's fair to ask "Tested or predicted?"

Armed with these definitions, you should be able to read a basic workout plan.