The Buddhist term śūnyatā (Sanskrit) is often translated into English as “emptiness”. Understanding the meaning of śūnyatā through learning the traditional logical arguments might seem daunting - difficult and time-consuming. Some teachers like to also use the term “openness” though, which suggests both the possibility of instantaneous intuitive understanding and of a broader (not merely intellectual) approach to practice.
Basic sitting meditation practice can be understood as training in “letting go”. There are many sources of instruction available, though the best way to learn is probably to meet an instructor in person.
Practicing virtue in everyday life is also a great way to help realize śūnyatā. The practice of generosity, for example, is one expedient means towards that end. What is generosity after all, if not “letting go”?
I think perhaps because of our cultural backgrounds, many of us feel like we’re stuck in some tug-of-war between satisfying our own needs and desires on the one hand, and punishing ourselves in order to “be good” on the other hand. Or we think we should be more humble, and when we try to do that it feels incredibly awkward. We might even subconsciously put on a serious face to prove how humble we are. But why should we do these things? If we don’t understand the nature of reality, then we will always be caught in this tug-of-war, and will tend to fluctuate between aggression and martyrdom. But we are not essentially separate from others, we are not singular in any way, and existence is made possible by impermanance. Impermanance isn’t something that chips away at our being - it is our being.
“Letting go”, and “opening up” sound pleasant enough, but these are extraordinarily difficult practices. The cultivation of mindfulness is a necessary component - “letting go” isn’t about relaxing and taking it easy. Our habitual tendencies continue to pop up all the time, and constant vigilance with respect to the functioning of the mind is a necessary tool. The instruction in the various techniques used by informed practitioners, as well as the finer points of the supporting philosophies fill volumes. As well, there is a long and illustrious history of noble people undergoing great hardships in order to record and preserve these teachings.