can someone explain to me the following:

How are equations with one variable to equations with two variables alike and how are they different?

They are alike in that there are two things that can vary. They are unlike in that a one variable equation does not vary, it has a unique solution.

Thank you for your explanation bobpursley. I really appeciated

You're welcome! I'm glad I could help. If you have any more questions, feel free to ask!