meal vs mustard in Korean
식사vs겨자

식사meal
식사 means a meal, or the act of eating a meal. It is a polite, common word you can use for breakfast, lunch, or dinner. You will often hear it in daily conversation, for example when asking if someone has eaten.
When to use meal
겨자mustard
겨자 means mustard, a strong and spicy sauce or powder made from mustard seeds. People often eat it with hot dogs, sandwiches, sausages, and other foods. In Korean, it can also mean the sharp mustard flavor used in some sauces and dressings.
When to use mustardHow they differ
식사 means a meal, like breakfast or dinner. 겨자 is something you eat with a meal, not the meal itself.