“denial.” The Hebrew is more literally, “robbery,” and denial of justice is a robbery, but we would not word it that way in English.
“in the land.” More literally, the “province” or “state,” but that does not communicate the Hebrew meaning as well as “in the land,” because when they thought of the “state” of Israel, it was the whole country, but a “state” to a Western reader does not have that as a primary meaning.
“amazed.” The Hebrew word translated “amazed” is tamah (08539 תָּמַה). Tamah has a whole range of meanings. In this kind of context, there is no one single English word that captures the meaning, rather the verse is saying that when we see oppression and a denial of justice we should not be “amazed” (or, “astounded, stunned, surprised, dumbfounded, shocked, or wonder or marvel”) at the situation. We live in a fallen and evil world and until Christ reigns as king there will be all kinds of injustice on earth.
“watches over another authority.” Even people in high positions have people over them watching them. There is also the possible meaning that “watch” is actually “watch over, protect,” which is a meaning of the Hebrew. In that case, the point the verse is making is that evil is throughout the system, and when a lower official perverts justice, officials above them often protect them for various reasons, thus making the whole world’s system corrupt, which is certainly true in a sense. If both meanings are indeed being set forth in the verse, it is an amphibologia, where one thing said has two true meanings.