Admission committees look for leadership skills in an applicant, both undergraduate and postgraduate and this can be shown in various ways.
Narrate your achievements as a leader. You may be a team leader within an organization or outside. For example, you could be the leader of an academic project, a sports team captain, organize a food drive or any community service based activity. It could be that you improved the work environment, helped build the brand, streamlined investments, enabled or empowered your team members.
Note, you must mention measurable results, like the size of your team, percentage increase in sales or clients etc.
If you have not been in the role of a team leader, but were an ad-hoc leader for an individual project or perhaps you did not have an official position, but were the driving force behind the project, you could still show your leadership quality. Show individual initiative.
Here it would be useful to have your recommender vouch for your claims.
If you have not led a group of people, don’t loose hope. You can inspire/motivate others/peers or help someone solve a problem, contribute to the growth of an organisation or project to show that you have leadership potential.
Note, it is important to narrate the episode/story rather than just list your accomplishments.