"Walk-on" is the term used to describe a particular type of athlete, especially in American college sports. This refers to college athletes who play without a scholarship on a team that offers scholarships. This means they do not receive financial aid because they do not have an athletic scholarship. The case can occur when an athlete comes from a smaller high school, for example, and therefore has not caught the eye of talent scouts. It is often the case that walk-on players act as reserve players and usually, they do not travel with them to away games.
Sources: https://www.diycollegerankings.com/what-is-a-walk-on-player-in-college-sports/7081/, https://usatodayhss.com/2017/the-5-most-commonly-asked-questions-about-being-a-college-walk-on