The term expression can refer to a variety of meanings, depending on its context. In general usage, it may refer to an outward appearance or manifestation of one's emotions, such as a smile or frown being expressions of happiness and sadness respectively. It could also indicate the act of expressing something through verbal or written communication, for example "giving expression to one’s thoughts" means conveying what is on your mind. In artistic contexts, an expression refers to the way a person's face looks in a particular emotion, such as anger, joy, sadness etc., which can be used to convey meaning or evoke emotions from viewers.
In computer programming languages, "expression" usually means a combination of values and operations that produce one value based on certain conditions. In mathematics, an expression refers to the sum or difference of two or more terms, typically including constants, variables, and operators such as addition, subtraction, multiplication, division, etc.
In summary, the term "expression" can have different meanings depending on its context, ranging from outward manifestations of emotions to mathematical equations or computer programming language operations.