JSFiddle - React, Tailwind, and code Playground

JavaScript

const badVals = ['-', 'na'];

const arr = [
  {
    "waste ": "",
    "d_f": "-",
    "sa": "  - ",
    "fgdf-h": "na",
    "gdws": "0",
    "ffd ": "121.4",
    " tg": "34",
    "yyy rd": "1,23 ",
    "abd": " 45678",
    "abd": " 4.567,8",
    "edf": " na",
    "first": "-   ",
  }
]

const newArr = arr.map(entry => {
	Object
  	.keys(entry)
    .forEach(key => {
    	 const val = entry[key].trim();
       if (badVals.includes(val)) {
       		entry[key] = null;
       }
    })
	return entry;
});

console.log(newArr);