Certain credit cards come with a low introductory interest rate for new cardmembers. Applicants with a very good credit score may even qualify for a 0% intro APR. Any transactions you make during the promotional period accrue interest at the lower introductory rate.
If you have a large purchase planned (think appliances, vacations, or other major expenses), a new credit card with a low introductory APR may make it easier to cover those costs comfortably. But to avoid accruing interest, stay on top of your monthly payment. Any balance that remains when the promotional period ends accrues interest at the standard rate.
Applying for a new credit card with a low-interest balance transfer offer may also help you get your existing credit card debt under control, as long as you have a good credit score.