The speaker tells us that their name isn't a word you can look up but a song. Where we expect a list of family names, we get long strings of vowels and breathy sounds: the father is a sound, the mother is a sound, and the speaker's own name is one too. The poem seems to imagine a kind of identity that comes before ordinary language, one passed down as music rather than spelling.
The feeling is calm, proud, and a little awe-struck. The opening line, "I swim in the great, the vast," suggests the speaker feels held by something much bigger than themselves, and the stretched-out sounds on the page almost work like waves or chanting. The ending states the idea plainly: the name is "a song of my ancestors / singing through me." The speaker doesn't feel alone or cut off. They feel like a channel for many voices at once. Reading it aloud, slowly, is probably the best way to catch that sense of belonging.