Brick and mortar (B&M) refers to a company which possesses a building for operations. The phrase can be a misnomer since not all buildings are physically constructed from bricks and mortar.
In the jargon of eCommerce, brick and mortar businesses are companies which have a physical presence (for example, a building made of bricks and mortar) — which offer face-to-face consumer experiences. This term is usually used to contrast with a transitory business or an internet-only presence (see online shop for comparison). An example would be the brick and mortar movie rental shop Blockbuster Video — the competition from the new online rental services offered by Netflix.
A comparable term in the United Kingdom is High Street shops, although the phrases brick(s) and mortar business are also used.