There is a special type of law enforcement officer, called a "bailiff" who is charged with maintaining order in a courtroom, and often, a bailiff is a direct subordinate of a judge who must follow the judge's orders.
Judges can also issue special kinds of court orders, called "writs" which are a direction to a law enforcement agency generally to take certain action. But, in these cases, the law enforcement agency is effective an "independent contractor" in relationship to the judge with considerable discretion regarding precisely how and when a writ is carried out. Somebody in the law enforcement agency to which a writ is directed is required to take action, but no individual law enforcement officer is personally compelled to comply with this order.
The quote in question is not a statement about the legal authority of a judge, however. It is a statement of "realpolitik". The judge can't physically force or threaten law enforcement to do what they are told to do by a judge. The cops have the guns, not the judges.
Instead, the judge relies upon law enforcement obeying the judge's orders because that is what law enforcement officers do. It's right in the job title. But, if law enforcement chose to ignore judges, in general, there is very little that judges could do about that (and in some countries, law enforcement does routinely ignore judicial directions).
Some forms of executive branch authority to defy judicial orders is even legally codified, most starkly in the case of the pardon power.