Semantics is the study of meaning. Meaning in this case refers to the relation between signifiers and what they stand for. Signifiers are words, signs and symbols.
The word semantics was first used by a French man named Michel Bréal. He studied the way that language was put together, how language changed as time passed, and the connections in languages. Semantics can include simple or very complicated ideas. In everyday speech, it means a problem with understanding language that can confuse because of the words or their connotation (another idea created by a word that is not in its definition). This problem of understanding has been studied for a long time, especially in the field of formal semantics, where people explain the connection between words and their meanings in a clear way.