Which mental representation would we need to utilize to think about abstract words like time, ambivalence, and fatigue?

The correct answer is concept

The concept is that which is conceived in thinking about something or someone. It is the way of thinking about something, consisting of a type of appreciation through an opinion expressed, for example, when a good or bad concept of someone is formed. In this case, concept can be synonymous with reputation.

It can also be interpreted as a mental symbol, an abstract notion contained in each word of a language that corresponds to a set of characteristics common to a class of beings, objects or abstract entities, determining how things are.

The concept expresses the qualities of a thing or an object, determining what it is and its meaning.

The words in several languages have the same meaning because they express the same concept.