Hi Shyam,
You could create 3 copies of the first marketing form, then change fields label to corresponding language for each form.
e.g:
By default, there are already 3 form fields: First Name, Last Name and E-mail.
In second form, we can just change their label to different language.

Live result
1 English

2 French

Another solution is to translate label text by javascript.
In marketing form, field label is rendered in Label tag, so our javascript function process is below:
1. Fire our custom function after form is loaded. (Check how to use Marketing form API here.)
2. Detect browser language of user by navigator.language function.(This table listed all possible return result in its Code column.)
3. Create multiple arrays to save translation text, each array is for one language.
4. Change label text to corresponding language by switch statement.
You could add code(jQury version) below to your marketing page to test whether it could work for you.(Change your browser language to French to test.)
MsCrmMkt.MsCrmFormLoader.on('afterFormLoad', function (event) {
// detect browser language
var currentLanguage = navigator.language.toLowerCase();
// Create an array to save translation text, each array is for one language
var frTranslation = ['Prénom', 'Nom de famille', 'Courriel'];
/**
* add other translation text
* var deTranslation = ['', '', '']; ....
*/
// Field label is rendered in Label element.
var totalLabel = $('label').length;
switch (currentLanguage) {
case 'fr':
case 'fr-fr':
case 'fr-ca':
for (var i = 0; i < totalLabel; i ) {
$('label').eq(i).text(frTranslation[i]);
}
break;
case 'de':
case 'de-de':
case 'de-ch':
break;
default:
break;
}
});
Regards,
Clofly