Этот лайнер:
const filtered = Object.fromEntries(Object.entries(data[0]["Count"]).filter(([k]) => result.includes(k)))
С поддержкой ES5:
const filtered = Object.keys(data[0]["Count"]).filter(k => result.includes(k)).reduce((acc, k) => (acc[k] = data[0]["Count"][k], acc), {})
Демо:
let data = [{
"Count": {
"Grapes": 1,
"Banana": 6,
}
}]
let result = ["Banana"]
const filtered = Object.fromEntries(Object.entries(data[0]["Count"]).filter(([k]) => result.includes(k)))
const filteredES5 = Object.keys(data[0]["Count"]).filter(k => result.includes(k)).reduce((acc, k) => {acc[k] = data[0]["Count"][k]; return acc}, {})
console.log(filtered);
console.log(filteredES5);