The Myers-Briggs Type Indicator (MBTI) is a trademarked psychological assessment tool that was devised by Katharine Cook Briggs and Isabel Briggs Myers. Having studied Jung’s theory of psychological types, they believed that his ideas were worthy of a wider audience and sought to refine them for practical purposes.
https://mbti-notes.tumblr.com/
check this out if you wanna learn more
Here's an easier read just use the 'personality type' button - https://www.16personalities.com/isfj-personality
Theres a reason its not used as a profesional test. Its widely unreliable with huge overlap between the types giving diffrent results for the same person each time. It also can't be validated as it doesn't really measure anything.
Its considered nothing but pseudoscience.
16pesonalities.com is not actually a Myers-Briggs test, is a big 5 test masquareded as a MBTI, and from what i heard alot of people who take MBTI seriously aren't the biggest fans of 16personalities.com
here for more on the big 5 https://www.truity.com/book/big-five-personality-model
here on why self-report questionnaires are imperfect https://mbti-notes.tumblr.com/basics#tests