A/B testing allows you to test variations of your page to see which one performs the best. But Please do not that in order to use A/B testing feature, you would need "Everything You Need Plan" or "Rapid Growth Plan."
Read these helpful and insightful articles on: How to A/B Test your Landing Page to Maximize Conversions & 15 A/B Testing Stats that will Blow Your Mind
For landing pages, A/B testing feature can be found on the top right corner of your editor, next to settings. Clicking the A/B testing tab will immediately create a variation that you can customize.
You can duplicate current variation, delete current variation, and rename current variation.
If you click the gear icon to the right of your variations you can select a winner based on your stats (Probability of Winning)