This allows you to change the text in your CTA buttons to reflect a benefit to visitors, rather than a long boring task that they will have to do.
e.g Sign Up → Increase Your Revenue!
Imagine two simple buttons displayed on a page. One button tells you that it will “Save You Money”, while the other one asks you to “Sign Up”. The first one is more likely to be acted on and convert visitors.
The reason for this is that "Sign Up" on it’s own has no inherent value. Instead, a sign up process takes effort and is often associated with lengthy forms of some sort.
The hypothesis set here is that buttons which reinforce a benefit might lead to higher conversions.
Usually, by including a benefit in your button text, you are also making a promise to your visitors. Make sure not to overlook this, because in case you are not able to fulfill your promise (e.g Increase Your Revenue!) your visitors may lose trust, or may even think your "benefit" is too good to be true.