Write x a^ f(x) in sentence.

The limit ${\lim }_{x\to a^{-}}f(x)$ is read as "the limit of the function $f(x)$ as $x$ approaches $a$ from the left."

In simpler terms, it represents the value that the function $f(x)$ gets arbitrarily close to as $x$ moves towards $a$ from values less than $a$ (i.e., from the left side of $a$ on the number line). This is called the left-hand limit of $f(x)$ at $x=a$.

For example, if $f(x)=\frac{1}{x}$ and $a=0$, then ${\lim }_{x\to 0^{-}}f(x)$ means the behavior of $f(x)$ as $x$ approaches 0 from negative values (e.g., $-0.1,-0.01,-0.001$), which tends to $-\infty$.