What does it mean for something to be true? You might be inclined to suggest that it is a factual representation of the world, so sure. Let’s go with that. How do we know that something is a factual representation of the world? Well, we’d have to figure out what it means to know something. The general consensus is that to know something is to hold a justified, true, belief. Let’s examine some controversy.
The Gettier Problem is a criticism of the justified, true belief model of knowledge. It is best explained using an example. A shepherd is tending his flock, and he checks in to see if all are present. He counts all but one, and then sees his last sheep on a hill in the distance, and thus knows that all his sheep have been accounted for. However, what he thought he saw was actually a dog, though his sheep was just on the other side of the hill, out of sight. The shepherd was justified in his belief since he did see something, and his belief was true since the sheep was indeed on the hill, but we would never claim that he knew his sheep was on the hill since he was mistaken in his observation.

No one suspects the slightest!
I want to examine the ‘truth’ statement of the Gettier Problem, rather than its epistemological connotations. The sheep is only ‘truly’ on the hill because I placed it there as the author of this thought experiment, but in any real life situation completely removed from the abstract, how would we know that it is true? In order for it to be true, we would have to know it to have that property, and in order for us to know about that property, it would have to be true. Truth and knowledge become a chicken and egg infinite regress when we take the lessons of the Gettier Problem and infuse them into real life situations.
There are further problems with truth. Consider counterfactuals. Counterfactuals represent statements that are true, but do not offer a factual representation of the world. For example, if I say, “The cup is red,” and we can all see that the cup is red, it is a true statement because the cup in the world is red, and my statement is a factual representation of that. However, if I say, “If America focused on the popular vote rather than the electoral college, Hilary Clinton would be president,” it is still a true statement, but it is not a representation of anything in this world. Philosopher David Lewis postulated that if we wish to maintain truth as a factual representation of the world, counterfactuals must rely on alternate universes to which these statements must refer. So we either accept that infinite alternate universes exist, or we accept that truth as a representation of the world is an unfounded premise.
Lastly, let’s look at the Liar’s Paradox. “This sentence is false.” If the sentence is true, then it is false, and if it is false, then it becomes true. If something must be true or false (and how could it be both? Or worse yet, neither?), then the Liar’s Paradox frustrates the notion of truth further. However, let’s look at “This sentence is false” in the context of language rather than of truth, and compare it to, “Colorless green ideas sleep furiously.” Both sentences are grammatically accurate, and seem to point to things in the world, but both are equally nonsense. Something green cannot be colourless, nor can an idea possess either of those characteristics, nor can an idea sleep, nor can the process of sleep or ideas be angry.
Statements of any kind do not point to things in the world, but to mental imagery. For example, the Nile river is still the Nile river if it floods, if it becomes diverted or dammed, or becomes polluted to the point where there are more arsenic molecules than H20. “The Nile river” refers to our idea of “The Nile river,” regardless of its properties in the real world. “The cup is red” refers to our ideas of cups, redness, what it means to be, and the specificity of “the”. It’s not pointing to the cup in the world at all. This makes the problem of counterfactuals much less relevant, since language, no matter its use, can only ever point to mental imagery. It also negates the Liar’s Paradox, since mental imagery does not have to be coherent to the same degree as real world objects. We are not observing any objective falseness, nor analyzing a sentence in the world; both exist only in our minds.
The truth, then, is not a factual representation of things in the world, since that premise is riddled with problems and ultimately unknowable. Thus the truth is our mental understanding of what a thing means to be true.