The @api decorator in the child component exposes a property, making it public, so that the parent component can update it. Similarly, @api decorator function in child component can expose it as public to call it from the parent component. Sample Code: childLWC.html: childLWC.js: childLWC.js-meta.xml: parentLWC.html: parentLWC.js: parentLWC.js-meta.xml: