A general class will consist of members arriving early enough to bitch about yesterdays workout and how sore they are lol. There will be a 10-15 minute warm up depending on the workout of the day. Most gyms will then have a heavy lift (bench, press, squat, deadlift, snatch, clean) these are generally more in power lifting rep ranges 6 reps or under. There will be a short break, then the WOD (workout of the day)
Most WODs are designed to push your aerobic and anaerobic energy systems with an almost infinite combo of runs, rows, bikes, lifts, and gymnastics movements. WODs are generally 8-15 minutes in length done for max reps or max speed. After this there will be a cool down bringing the total class to about an hour.
Some gyms do it differently but this is the general template.