What does this tagged template literal log?

function tag(strings, ...values) {
  return strings.reduce((acc, str, i) => {
    return acc + str + (values[i] !== undefined ? `[${values[i]}]` : "");
  }, "");
}

const name = "World";
const count = 3;

console.log(tag`Hello, ${name}! You have ${count} messages.`);