Answer
As $x\to -\infty $ , $f\left( x \right)\to 1.$
Work Step by Step
The horizontal asymptote $y=a$ means the function tends to $a$ as $x$ tends to $+\infty $ or $-\infty $.
In the graph $y=1$ is a horizontal asymptote. So, the function $f\left( x \right)$ tends to $1$ as $x$ tends to $-\infty $.