Beith, or Beth, corresponds to the letter B in the alphabet, and is associated with the Birch tree. When this symbol is used, it is representative of new beginnings, change, release, and rebirth. In some traditions, it also has connections with purification.
Birch trees are hardy. They'll grow just about anywhere, including on bare soil. Because they tend to grow in clusters, what may be just one or two seedlings now can be practically an entire forest in a few decades. In addition to being a sturdy sort of tree, the Birch is useful. In days gone by, it was used for infants' cradles, and is still harvested today to make cabinets and furniture.
From a magical perspective, there are a number of uses for Birch. The branches are traditionally incorporated into the construction of a besom, and are used for the bristles. Use the white outer bark in ritual in place of paper or parchment -- just be sure you only harvest the bark from a fallen Birch tree, not a living one. Ancient herbalists discovered that various parts of this tree can be used for medicinal purposes. Bark was once brewed into a tea to fight fevers, and the leaves were used alternately as a laxative and a diuretic, depending on how they were prepared.
Mundane Aspects: When this symbol appears, it means it's time to get rid of all those negative influences you've been carrying around with you. Figure out what things are bad in your life, which relationships are toxic, and find a way to leave them behind. Instead of being dragged down by the negative, focus on the positive things you have in your life, the blessings and abundance. Use these things as a focus, rather than the harmful or damaging ones.
Magical Aspects: Consider the property of renewal and rebirth, as demonstrated by the Birch. Use this as a tool for spiritual and emotional regrowth, and developing your own ability to regenerate where there has been emptiness or devastation.