This is a combination of the concepts of "term life" and "a savings account with interest."
The insurance company lets you take out a policy that typically renews every year, meaning that the premium goes up, every year. But—they also let you put money into this tax-deferred savings account called a "sub-account" that makes it to where you can stop paying those term premiums after a certain year or just build up a crazy amount of money inside the policy as if it were a bank.
Sounds great, right? Well, the entire idea took a big hit when interest rates fell hard-core. Mostly because the people who made these policies couldn't imagine a world where prime interest rate could fall below 8%. Guess what? It did.