The "heart" here refers to the mind and thoughts of the person. AT: "so that you are not occupied with" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
Jesus here speaks of the following sins as if they were a physical weight that a person had to carry. (See: [[rc://en/ta/man/translate/figs-metaphor]])
Just as a trap closes on an animal when the animal does not expect it, that day will happen when people do not expect it. AT: "that day will happen when you are not expecting it, as when a trap closes suddenly on an animal" (See: [[rc://en/ta/man/translate/figs-simile]])
The coming of that day will appear to be sudden and unexpected to those who are not ready and watching for it. AT: "For if you are not careful, that day will close on you suddenly" (See: [[rc://en/ta/man/translate/figs-explicit]])
The surface of the earth is spoken of as if it was the face of a person. That is, the outward part. AT: "on the surface of the whole earth" or "on the entire earth" (See: [[rc://en/ta/man/translate/figs-metaphor]])