Answer
$(-\infty, 6]$
Refer to the graph below.
Work Step by Step
The conjunction "or" means union.
Recall:
The union of sets $A$ and $B$, denoted by $A\cup B$, is the set that contains the combined elements of $A$ and $B$.
$x\le-2$ includes all real numbers less than or equal to $-2$.
In interval notation, the set is $(-\infty, -2].$
$x\le6$ includes all real numbers less than or equal to $6$.
In interval notation, the set is $(-\infty, 6].$
Thus, the union of the two given sets is $(-\infty, -2] \cup (-\infty, 6]$, which when simplified becomes $(-\infty, 6]$.
To graph this solution set, plot a solid dot at $6$ then shade the region to its left.
Refer to the graph above.