"heaven" and "earth" represent everything that exists. AT: "Master over everyone and everything in heaven and earth" (See: [[rc://en/ta/man/translate/figs-merism]])
This refers to Jesus' previous teaching about the authority of the disciples. It may be best to simply say "these things" and let the reader determine the meaning.
The words "wise" and "understanding" are nominal adjectives that refer to people with these qualities. Because God had concealed truth from them, these people were not actually wise and understanding, even though they thought they were. AT: "from people who think they are wise and have understanding" (See: [[rc://en/ta/man/translate/figs-irony]] and [[rc://en/ta/man/translate/figs-nominaladj]])
This refers to those who may not have much education, but who are willing to accept Jesus' teachings. AT: "people who may have little eduction, but who listen to God" (See: [[rc://en/ta/man/translate/figs-ellipsis]])
"as little children." People who know that they are not wise and knowledgeable are willing to be taught, as children are willing. (See: [[rc://en/ta/man/translate/figs-simile]])