Sextiles connect signs of compatible elements, such as fire with air or earth with water. The planets involved understand each other well and tend to help one another with little friction.
What sets the sextile apart is that it works like a door left slightly open. It offers possibilities, but you usually need to give it a small push. A sextile between Mercury and Mars, for example, can make it easier to argue a point with energy, and that skill grows the more you use it, whether in a lively debate or a project that asks you to make your case.
It is gentler than the trine and less obvious. Many people find their sextiles in hindsight, noticing that certain things simply went well without much strain. When reading a chart, it helps to ask what talent a sextile points to and how you might give it more room in daily life.