It looks like you have used some contact form plugin for the form. So, while creating a form from that plugin you can select language for the form like this contact form plugin does (https://wordpress.org/plugins/contact-form-7/) and all the form text will be in that selected language. Alternatively, you can use a WordPress function which translates texts (https://codex.wordpress.org/Plugin_API/Filter_Reference/gettext). For example:
To change ‘Name’ to ‘First name’, just add the below codes in ‘functions.php’ of child theme.