Lots of instructors, including myself can be guilty of speaking in acronyms, or saying words that we understand, where beginners might have no clue (a bit like how sometimes my friends who work on corporate businesses say things that just sound made up to me!)
So, I'm going to put some things here to say what they all mean in my own wording (so do forgive if it's not exactly as google!). Please ask if I've missed any out that you're not sure of - I'm sure there will be loads!
Reps - Short for repetitions. How many times you do (or repeat) an exercise. For example, if I do 10 Squats that's 10 reps.
Sets - How many times I do the reps. For example if I do 2 sets of 10 squat reps. I do 10 squats, have a break, and then do another 10.
Pyramid - This is where you start with a low number of reps, gradually build to a higher number of reps, then work your way back down again. For example, 2 squats and 2 push ups. Then 4 of each, then 6 of each then back down to 4 of each and 2 of each.
EMOM - This stands for every minute on the minute. For example, if you did a 10 minute EMOM of 10 squats and 10 push ups, as soon as the timer starts you complete the exercises. You then rest until the next minute begins and you repeat for the set amount of time.
AMRAP - This stands for as many rounds as possible. For example if you did a 10 minute AMRAP of 10 squats and 10 push ups you would just continually complete those exercises, only taking rest where required until the timer is up.
RPE - This stands for rate of perceived exertion. It's a scale system used to try and work out how hard you're working where 0 would be sitting down, and 10 would be your maximum effort.
Tempo - This is the speed that you do an exercise. It can be written in 2 ways. So for example, if you do a squat and you take 4 seconds to get to the bottom, and 1 second to get back to the top and you have no pause at the bottom or the top it can be written as either 4-1 or 4-0-1-0. Changing the tempo of an exercise can change the intensity.
DOMS - This stands for delayed onset muscle soreness. It's when your muscles ache, but it tends to come on after 24 hours post exercise and might get worse. It's very normal, but they don't know loads about why it's sometimes delayed, why it sometimes isn't, or why sometimes we ache and sometimes we don't. Your post exercise soreness doesn't necessarily correlate to how hard you work.
HIIT - This stands for High Intensity Interval Training. It's where you do an exercise at a really high effort followed by a recovery period and you repeat. It's a type of training that can really improve your heart and lung capacity and your explosive power.
LISS - This stands for Low Intensity Steady State. It's where your exercise is low effort, and the intensity doesn't vary but stays the same. For example going for a walk, or an easy bike ride. It's where your heart rate stays quite low and level throughout. This is great for improving your endurance.
Cardio - This is a type of training that gets your lungs and heart rate (or cardiovascular system) working. For example, running, swimming, cycling, cross trainer, boxing etc.
Weight/Strength/Resistance Training - Using resistance (body weight, bands, objects, weights) to make your muscles contract and overtime build strength in muscles and joints.
Progressive Overload - This is when you continuously make an exercise harder to keep loading your muscles more and get stronger. For example, you can change the tempo, the number or reps, the number of sets, or increase the weight.
Drop Set - This is when you're performing an exercise with a weight, and when you can't perform it any longer you then make the weight lighter so you can do a few more. And then you repeat continuing to drop the weight. It's a good way to build strength as it means you're still working your muscles where you would have stopped otherwise.
Super Set - This is when you perform 2 exercises back to back with no rest in between. It is generally targeting the same muscle group (for example the legs).
Tri Set - This is when you perform 3 exercises back to back with no rest in between.
Giant Set - This is when you perform 4 or more exercises back to back with no rest in between.
Circuit Training - This is a bit like a Giant Set in that it's multiple exercises back to back with little to no rest, but it's usually across different body parts or maybe sometimes weights, sometimes cardio.
ROM - This stands for range of motion. In the example of the squat, it will be how low each person can squat with good technique and without pain.
RPM - This is a measurement on a bike, it stands for rotations per minute and it's how many times your legs will pedal round in one minute.
WOD - This stands for workout of the day! It's just where someone will share a workout that everyone can do that day and usually changes every day.
And I'm realising this is probably about as boring as reading the dictionary, so I will stop here. But again, do ask if there's anymore you're not sure of!