EShop supports captcha for some parts on the front-end side. Please go to EShop -> System -> Configuration -> Options tab, you will see the setting options to turn them ON/OFF: So they are:
EShop is using Joomla core captcha plugins: reCAPTCHA and invisible reCAPTCHA. So after enable captcha in EShop, you must also enable and configure the captcha in Joomla to make it work properly. Please read about to set up Google reCAPTCHA & invisible reCAPTCHA in Joomla at https://docs.joomla.org/J3.x:Google_ReCaptcha