This refers to a grammar structure used to talk about an ‘unreal’ or ‘unlikely’ situation. The situation is unreal which means you are imagining the situation. This conditional provides an imaginary result for a given situation.
The grammar structure is:
If-clause: if + past tense (was, didn’t have) Main clause: would or wouldn't
If my grandmother was alive, she would be 90 years old. (She is not alive. she died 15 years ago.)
If I didn’t have a car, I would find it difficult to get about. (The real situation is I have a car.)