Meditation is extremely simple. Sit down (ideally), in a comfortable but alert position. Close your eyes. Focus on your breathing. When distracted return your focus to your breathing.
Perhaps use a mantra (a specific phrase) when breathing e.g. the Moot Community in London, who taught me to meditate, suggest using ‘Mara-natha’. Say this to yourself (not out loud) as you breathe in (Mara) and out (-natha).
There are a variety of approaches from East and West, spiritual and secular; but they all advocate a very similar practice, the understanding and goals vary.
There seems to be a growing scientific consensus that meditation has concrete benefits to mental and physical health.