The speaker describes a day taken over by "accounts." The word could mean financial records, online profiles, or the duties of a job, and the poem leaves that open. Whichever it is, the opening line says it plainly: these things own the speaker, not the other way around. The whole afternoon belongs to them.
Then the poem shifts at night. The accounts "lie" there "like amber / keeping the heart." Amber is the golden resin that traps and preserves whatever falls into it, so the image suggests the heart is being held safe, but also held still. There's a quiet double meaning in "lie," too: the accounts rest, but they might also be untrue, or deceive.
The mood is dry, wry and a little uneasy. The speaker doesn't complain loudly. The title, "Self-preservation," makes the ending feel ambiguous: is this duty protecting the speaker's feelings, or freezing them in place? The poem lets us sit with both possibilities.