Press this and characters to the right of the insertion point are deleted. It may also be labeled Delete or Del, and it has the forward delete symbol on it: ⌦. On extended keyboards, you may also find a “forward delete” option.
(For Mac users, it’s nearly always Delete Backspace is more of a…Windows word.) On various vintages of keyboards, you might find the word Delete, a leftward-pointing arrow ←, or both the arrow and the label.
If you’re a long-time Mac user or a new one, it’s possible you’re only aware of the Delete key, which is technically a “backward delete”: it deletes characters to the left of the current cursor in English and other languages that read left-to-right.