I will tell you about the advantages and disadvantages of having
homework on a holiday. Advantage means something good that helps you while disadvantage means something that makes a situation more difficult.

    One of the advantages is when I got a perfect score on an important test and one of the disadvantages is when I failed on an important test. I experience a lot of good things in life. Doing good things is better than doing the opposite.
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Rachel: I will tell you about advantages and disavantages.
Correct: I will tell you about the advantages and disadvantages of having
homework on a holiday.
Explanation: We have to use the article the to refer to specific or particular nouns. In addition. we have to add something to your sentence to make it clearer.

Rachel: Advantage is a good thing. And disavantage is a bad thing.
Correct: Advantage means something good that helps you while disadvantage means something that makes a situation more difficult.

Explanation: The sentences should be a compound sentence. Use the conjunction while  to compare two different facts. Since the sentences are somewhat vague, we need to add more phrases/words to complete it.

Rachel: Advantage is like when I had a hundred score on the important tet. Disavantage is like when i had zero score on the important test.
Correct: One of the advantages is when I got a perfect score on an important test and one of the disadvantages is when I failed on an important test.
Explanation: There are a lot of advantages and disadvantages of some things, so we can use the expression, "one of the advantages/disadvantages..." to show that there are still some, but you are just telling one of them.

Rachel: I have lots of advantage things.
Correct: I experience a lot of good things in life.
Explanation: Using the word experience is better because it shows feelings.

Rachel: You should have lots of advantage things more than disadvantage things.
Correct: Doing good things is better than doing the opposite.
Explanation: Sometimes, we need to rephrase the sentences/words in a sentence to make it clearer.