There are some common elements of meditation that make meditation less abstract and you understand what meditations are trying to achieve for both the conscious and subconscious mind. Having an understanding of the different types of brain waves that occur during meditation and during life will be helpful.
The dominant brainwaves you are using right now while reading this are Beta brainwaves. These brainwaves correspond to active thinking or doing. Meditation takes into account that people are in a beta state most often these days and meditation needs to find a way of appealing to a persons perception at the level of these brainwaves. That’s why meditation will start with some kind of initial relaxation that involves scanning the senses or awareness of the breath to give beta brainwaves a different focal point that is less stimulating than all that is going on in your mind or your world.
Now that the brain is less concerned with the external environment and is moving away from your thoughts, the brain starts to relax and Alpha brainwaves become dominant. These are of a lower frequency, you remain alert but feel more relaxed, even drowsy. The meditation will be mainly keeping your awareness on your internal landscape whether that is the breath, a mantra, images or sensations but could also be an external sound that is predictable like relaxing music.
When the brain stays in this drowsy state of activity for a few minutes you will start to produce more Theta brainwaves. These are slower frequency again and produce dream like states. This is where we can find our creative and imaginative self but also where we access the subconscious mind and can understand and change our habits, values and beliefs.
Sometimes during meditation we may move into Delta brainwaves, these brainwaves are associated with sleep and may be just what you need in that moment, if fatigue is a feature in your life. Guided meditation will try keep you above the Delta threshold and to decrease the chances of falling asleep during meditation, practice sitting up. Usually your head will nod and you will move out of Delta territory back to Alpha.
While in Theta territory and accessing the subconscious mind, a thought, event or memory may become active (The spikes in the graph below). The release is powerful enough to increase brain activity and move you up to Alpha or Beta level. This is where we acknowledge the thought and move back to our anchor and the brainwaves will slow down again. By repeating this process we start to decondition our mind from fixed beliefs or attitudes and as a result develop a stronger level of open mindedness.

Note: This is not how it would look on an EEG as you are always producing all brainwaves at some level.
It is by accessing the subconscious mind we can use meditation for rewiring the brain, gaining fresh insight, dissolving dysfunctional behaviours and releasing us from our conditioned minds. It is during these lower frequencies of brain activity where the magic happens. The important thing is to give your mind a chance to move away from Beta level awareness Set up the conditions that make meditation possible – a quite space, phone off, a comfortable posture and then try softer.