Study this example situation:

Monica wants to start a catering career but she doesn’t have enough money to do so. She sits down and thinks about what her business would be like if she had the necessary financial support. She says to herself: “If I had 500 dollars I would buy the kitchenware I need to get me started.”

Monica doesn’t have the the money she needs to start her business. She is imagining a situation that will probably not happen. So she says “If I had…I would buy…).

When we talk about imaginary situations we use the Second Conditional (if + past simple + would + base verb form).

Please have in mind that the meaning is not past.

Could and might can also be used instead of would.