A home equity line of credit (HELOC) is a type of loan taken out against the accumulated equity in your property(s). A HELOC is not the same as a home equity loan in that the borrower is not advanced the entire sum up front. Rather a HELOC uses a line of credit to borrow sums that total no more than the credit limit allocated by a financial institution.
HELOC loans can be seen like a credit limit on a credit card - You're allocated a certain amount which you can then use on any purchases you like. Some cases might include using a HELOC to make home improvements, buy a new car, pay for educational expenses or other large expenses. Just like a credit card, you will make payments on a pre-determined basis which includes the principal an interest of the total loan amount.
HELOC loans come with a higher than standard interest rate, so are generally not used for minor purchases or day to day expenses.