Bicarbonate of soda is a raising agent: in contact with an acidic ingredient (yogurt, lemon juice, vinegar) it releases carbon dioxide and makes doughs rise. That is why it works well in vegan baking, with a little apple cider vinegar or lemon juice.
You need very little, half a teaspoon for a shortcrust, or it leaves a bitter aftertaste. It is also useful for washing fruit and vegetables and kitchen cloths.