What is the difference between independent and dependent variable

Independent means that it does not depend on, does not rely on, is not affected by anything. A dependent variable is a variable is affected by some other variable. If. the independent variable happens to change its value, the dependent variable must comply and change also according to the rule that connects the two variables.
An example of independent variable is time. It runs its course, not affected by anything else.
Maybe a money example will be more transparent.
Suppose you have a part-time job to support you in your studies. In a part-time job, the number of weekly work hours is not fixed in advance. Some weeks you are relatively free and can work more hours. Other weeks you have exams and can't do as much.

Let us consider the situation: your weekly salary. You understand that your weekly salary will vary in relation to the total number of hours you work during a given week. The more you work, the more you earn. The less you work, the less you earn.
Clearly there is a link between the number of work hours, and the weekly salary. You have two quantities that vary from week to week. They vary: so they are called variables (variable= capable of varying/changing its value).
The two variables are x= number of hours worked in a given week, and y= weekly salary earned in the same given week.
You and only you can decide of your own free will on the number of hours you will work that week. However, once you choose/decide how many hours you will work, your salary is calculated according to a set rule your boss and yourself had agreed to.
Of the two variables in the situation describing you weekly salary, the number x of hours worked is the independent variable. The weekly salary y is the dependent variable: the amount of money you get depends on/ is decided by the number of hours you worked.

Please use a dictionary to see the meaning of the verb to depend on, and the adjectives dependent, independent.