When someone says, "You should be more ambitious," they are suggesting that you should set higher goals and have a stronger desire to achieve success or accomplish more in your life. The term "ambition" refers to a strong drive or determination to achieve something significant or to reach a certain level of success in one's personal or professional life.
By encouraging you to be more ambitious, the person is likely implying that they believe you have the potential to achieve more than you currently are or that you may be selling yourself short. They may feel that you are not fully utilizing your abilities and talents to their fullest extent.
This advice could apply to various aspects of life, such as career aspirations, academic pursuits, personal development, or even in the pursuit of dreams and passions. Essentially, they are suggesting that you set higher expectations for yourself, strive for greater accomplishments, and work harder to achieve your goals. It's an invitation to be more proactive, determined, and focused on achieving the best possible outcomes in your endeavors.