The subjunctive mood is a verb form that is used for unreal or hypothetical statements. It is made up of the phrases I were, he were, she were, it were, etc. You often use this form when you are being wishful. For example,
I wish I weren’t so shy.
I wish it were warmer outside.
If I were taller, I could dunk a basketball.
If John were a rich man, he could drive a fancy car.
He acts as if he were the one in charge.
John spends money as if he were a millionaire.
All of the above sentences use the verb were because they aren’t true; they do not describe reality.
In the first two sentences, I am talking about things I wish would happen.
In the third and fourth sentences, I am talking about situations that would happen if I were taller and if John were rich, speaking hypothetically.
And the fifth and sixth sentences are examples of unreal statements.