Mindfulness means paying attention in a particular way -- on purpose, in the present moment, nonjudgmentally.
The practice of mindfulness does not contradict any specific belief, tradition, religion, or culture. It is simply a focused and intentional way to notice thoughts, mental images, physical sensations, sights, sounds, and other details of our present moment experience that we may not otherwise notice.
While the actual skills may be simple, for many the practice of mindfulness can be difficult because it's not how we normally attend to our lives. We may be constantly pulled toward thinking and worrying about the future, or remembering and ruminating about the past. We may be focused on all that is "wrong" with us or our lives, and absorbed in our suffering.
Developing the ability to focus our full attention on the present moment without any judgment that things "should" be different in some way, has been scientifically shown to be an effective way to reduce stress, increase clarity and self-awareness, and manage painful thoughts, emotions, and bodily sensations.
Mindfulness practice will not eliminate life's pressures, but it will provide the ability to respond to them in a calmer, more effective manner.