const marks = {
harry: 98,
rohan: 70,
aakash: 7
};
for (let key = 0; key<Object.keys(marks).length; key++)
console.log('the marks of ' + Object.keys(marks)[key] + ` are ` + marks[Object.keys(marks)[key]]);
/*
Output:
the marks of harry are 98
the marks of rohan are 70
the marks of aakash are 7
*/