If your company is a public, then equity is easy to value equity. Look up what the share price of your company is and multiply it by the number of shares you’re receiving.
If your company is a private then you cannot value your equity publicly. You have to rely on internal company metrics to be able to calculate the value of it.
Ask the company for the 'strike price' and the 'share price.' The share price is how much the equity is worth. The strike price is how much you’d have to buy the equity for. Subtract those two numbers and multiply them by the number of shares to get the value of your equity.
It is common for equity to vest over a number of years with a cliff. Typical is a 4-year vest 1-year cliff. This means that before you stay at the company for 1 year, you will receive 0 equity. Then at the one year mark, you receive 25% of your equity. You’ll receive all your equity at the end of 4 years.
Remember, you have to buy your equity. So if you stay for a year but don’t have cash to buy your options, you’ll walk away with 0 equity.