So /effect is basically adding an effect to you. For example: /effect @s regeneration 10 100 true. @s you probably already know because, I explained it in an earlier command. Next is the regeneration. Regeneration is the effect of the thing. Like for example: Haste, strength, and levitation.
After the regeneration, is the 10. That is how much seconds it will go for. If you want to view how many seconds you have left, then just press “Z” On your keyboard to view all the effects.
Next is the 100. That is the amplifier an amplifier is how strong that effect is. Like If you do the amplifier for haste, 255, which is max, then it can break obsidian by hand in a millisecond.
Finally, it is the true. I might have explained this earlier, but I forgot. So Here: True = on = yes. And false = Off = no.
