union-arrays.js

const arrs = [ 
  ["General Fitness", "Health & Fitness"],
  ["Cardiovascular", "Meditation"],
  ["Health & Fitness", "Cardiovascular", "General Fitness"],
  ["Cardiovascular"]
];

const result = [...new Set([].concat(...arrs))];
console.log(result);

//example
  const arrs = dataQuery && dataQuery.map(
    item => item.translation.map(i => i.locale)
  )
  const result = [...new Set([].concat(...arrs))];
  console.log(result);