Try explaining about some interesting course you have taken during your Bachelor's Degree, give some explanations and state how it triggered your interest in the course your are applying for. You can also explain about your internships, what you have learnt, what you were exposed to and from there draw some conclusions about how you became interested in the course you are planning to apply to.
You can also explain about some challenges you faced during you Bachelor's Degree and how you overcame it. What did you learn from those challenges? How did it impact your path?
Or, you can talk about your relationship with the professors at your former university. Talk about your Bachelor's Thesis, your supervisor, what you learnt during this time, what you learnt from your supervisor and etc.
Usually universities provide you with a list of the things you have to write about. This one is kind of vague. Basically, they have left it up to you to talk about anything you wish to, so make sure you explain everything about yourself! Talk about your academic life and extra curricular activities as well, you can even go further and explain how you managed your time and balanced everything during your Bachelor.
Hope this helps!
