Cheat meals, broadly speaking, a meal or day during a planned period of dieting, wherein you eat as much of whatever you like.
'Cheat' in this instance means 'breaking the rules.'
The problem with breaking the rules you set you to reach your dietary goals is that the rules exist for a reason and serve your goal, and if you break your rules, you move farther away from your goal.
Not good...
HOWEVER,
There are potentially several benefits associated with varying the amount of food you eat, the kind of food you eat, or even from taking a break from strict dietary boundaries, depending on your goal.
For example, if you are using energy restriction (counting calories) to lose weight, there are measurable benefits to taking a short break from being in a deep energy deficit, such as preventing metabolic slowdown and increasing motivation.
There MAY be hormonal benefits to cycling into periods of high carbohydrate intake if you are deep into ketosis for long periods of time.
And, remember that we eat to live, and not the other way around. You can't be expected to never participate in social or holiday traditions involving food ever again. Planned dietary breaks can help teach you how to be flexible enough to manage these events and then quickly return to the tools that are moving you toward your goals.
Obviously, cheating can be problematic. Certain processed foods can cause withdrawal like symptoms and any cheating will just prolong that negative experience. It's also possible to overeat SO MUCH of the wrong thing during a cheat meal/day that you actually take a few steps back from your goal despite the benefit you may be receiving.
Whether or not you can fit a planned dietary break into your nutritional program is not something I can answer generally without talking to you first, but we'd love to help build something for you that works!
Also, if you mess up, and have a few, impromptu cheat days (or weeks) in a row... it's not over. And that's no reason to give up. Just start today, right now, and get back on the horse.
All you have to do to reach your goal is not give up.