Self-latching describes a latch that engages automatically when the gate reaches closed. The standard residential mechanism is a magnetic top-pull latch (Magna Latch is the dominant brand) where a magnet pulls the latch tongue into the catch as the gate gets within range.
AS1926.1 requires every pool-barrier gate to be both self-closing and self-latching, working together. A self-closing gate that doesn't self-latch isn't compliant: a kid could push the gate open and it would come back to closed but unlatched.
Latch position matters too. AS1926.1 requires the latch handle to be at least 1500 mm above the ground (measured to the lowest point of the handle), specifically so a young child can't reach up and unlatch the gate.