Fatal Error on wordpress membership page

Fatal error: Call to undefined function get_field() in /home/leaflyft/public_html/cannawaze.com/wp-content/themes/HighendWP-child/page-standard-membership-application.php on line 59

Hi so im sorry about freaking out on my last support ticket i didnt mean to come off so rude i was just panicking and extremely stressed out. But im having a issue on my memberships page could you please help me and explain how i can fix this error code i put above ?